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Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Bio Botany Guide Pdf Chapter 6 Cell The Unit of Life Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Bio Botany Solutions Chapter 6 Cell The Unit of Life

11th Bio Botany Guide Cell The Unit of Life Text Book Back Questions and Answers

Choose The Right Answers:

Question 1.
The two subunits of ribosomes remain united at a critical level of
a) Magnesium
b) Calcium
c) Sodium
d) Ferrous
Answer:
a) Magnesium

Question 2.
Sequence of which of the following is used to know the phylogeny
a) mRNA
b) rRNA
c) tRNA
d) HnRNA
Answer:
d) HnRNA

Question 3.
Many cells function properly and divide mitotically even they do not have
a) Plasma membrane
b) Cyto skeleton
c) Mitochondria
d) Plastids
Answer:
d) Plastids

Question 4.
Keeping in view the Fluid mosaic model for the structure of cell membrane which one of the following statements is correct with respect to the movement of lipids & Proteins from one lipid mono layer to the other
a) Neither lipid nor protein can flip flop
b) Both lipid and protein can flip flop
c) While lipid can rarely flip flop proteins cannot
d) While proteins can flip flop but lipids cannot ,
Answer:
c) While lipids can rarely flip-flop proteins cannot

Question 5.
Match the columns and identify the correct option:
Answer:

(a) (b) (c) (d)
(1) (iii) (iv) (ii) (i)
(2) (iv) (iii) (i) (ii)
(3) (iii) (iv) (j) (ii)
(4) (iii) (i) (iv) (ii)
Answer:
(3) (iii) (iv) (i) (ii)

Question 6.
Bring out the significance of Phase Contrast Microscope
Answer:
Phase-contrast microscope is used to observe living cells, tissues and the cells cultured invitro during mitosis.

Question 7.
State the Protoplasm theory
Answer:

• Fischer in 1894 & Hardy ( 1899 ) Proposed the Colloidal theory of Protoplasm (the physical basis of life)
• It is a colloidal system with water, many biological import things, glucose, fatty acids, amino acids minerals, vitamins hormones & enzymes are seen.
• Homogenous -These solutes are soluble
• Heterogenous – Solutes are not soluble – This Forms the basis for its colloidal nature.
• Protoplasm occur in 2 states but interconvertible

Question 8.
Distinguish between Prokaryotes & Eukaryotes.
Answer:

Question 9.
Difference between plant and animal cell:
Answer:

Question 10.
Draw the ultrastructure of a plant cell:
Answer:

Part-A

Choose The Right Answer:

Question 1.
Scientist who named the unicellular particles as ‘animalcules’ …………… .
(a) Aristotle
(b) Robert Brown
(c) Antonie von Leeuwenhoek
(d) Robert Hooke
Answer:
(c) Antonie van Leeuwenhoek

Question 2.
Compound microscope was invented by
a) Robert brown
b) Z. Sigmody
c) Z. Jansen
d) Zenike
Answer:
C) Z. Jansen

Question 3.
Micrometry is a technique of measurement of
a) Microtomy
b) Nanoparticles
c) Microscopic Objects
d) Moving objects
Answer:
c) Microscopic Objects

Question 4.
Which of the following electron opaque chemical is used in Electron microscope?
(a) Strontium
(b) Deuterium
(c) Palladium
(d) Uranium
Answer:
(c) Palladium

Question 5.
Who first observed Protoplasm
a) Corti
b) Felix Dujardin
c) Hugo Van Mohl
d) O. Hertwig
Answer:
a) Corti

Question 6.
Dinoflagellates and Protozoa are kept under
a) MegaKaryotes
b) Prokaryotes
c) Eukaryotes
d) Mesokaryola
Answer:
d) Mesokaryota

Question 7.
Which among the following is NOT an exception to cell theory?
(a) Viruses
(b) Viroids
(c) Prions
(d) Fungi
Answer:
(d) Fungi

Question 8.
Michondria was named by
a) A.kolliker
b) Altmann
c) Benda
d) Purkinje
Answer:
c) Benda

Question 9.
When Thylakoids are stacked together like a pile of coins known as
a) Grana
b) Cistemae
c) Quantosomes
d) Polysomes
Answer:
a) Grana

Question 10.
Dense particulars or granules observed by George Palade is known as
a) Cirtemae
b) Lamella
c) Locules
d) Ribosomes
Answer:
d) Ribosomes

Question 11.
Histone proteins are seen in the DNA of …………… .
(a) Pseudokaryotes
(b) Prokaryotes
(c) Mesokaryotes
(d) Eukaryotes
Answer:
(d) Eukaryotes

Question 12.
These are also known as Microbodies
a) Mitochondrial & Ribosomes
b) Ribosomes & Cistemao
c) Polysomes & Vacuoles
d) Peroxisomes & Glyoxysomes
Answer:
d) Peroxisomes & Glyoxysomes

Question 13.
The organelle made up of nine triplet peripheral fibrils are known as
a) Microbodies
b) Tululin
c) Centrosome
d) Centroles
Answer:
d) Centroles

Question 14.
Fungal cell wall is made of …………… .
(a) Cutin
(b) Chitin
(c) Hemicellulose
(d) Pectin
Answer:
(b) Chitin

Question 15.
‘Annule’ are circular structure seen around
a) Nuclear membrane
b) Nuclear Pore
c) Perinuclear Space
d) Annuli
Answer:
d) Annuli

Question 16.
The Chromosome that occur in the oocyte of Salamander and in Giant nucleus of Acetabularia is known as
a) Polytene Chromosome
b) Lamp brush chromosome
c) Mitochondrial chromosome
d) Chloroplast chromosome
Answer:
b) Lamp brush chromosome

Question 17.
Ordinary microscope can be made into Dark Field Microscope (DFM) by means of a special component is called
a) Patch stop carrier
b) Secondary Magnification lens
c) Stage
d) Phase plate
Answer:
a) Patch stop Carrier

Question 18.
In-plant cells, golgi bodies are found as small vesicles called …………… .
(a) Polysomes
(b) Cytosomes
(c) Cytosol
(d) Dictyosomes
Answer:
(d) Dictyosomes

Question 19.
Cisternae, tubule and Vesicles occur in which of the following:
a) Golgi apparatus
b) Lysosomes
c) Endoplasmic reticulum
d) Glyoxysomes
(i) a & b
(ii) b & c
(iii) c & d
(iv) a & c
Answer:
(iv) a & c

Question 20.
The Golgi apparatus in plant is known as
a) Dictyosomes
b) Glyoxysomes
c) Neo-particles
d) Microvesides
Answer:
a) Dictyosomes

Question 21.
Which of the three, come under the system of the membrane in Eukaryotic cell
a) Mitochondria
b) Nuclear Membrane
c) Golgi apparatus
d) Endoplasmic reticulum
(i) a, b & c
(ii) b, c & d
(iii) a, c & d
(iv) a, b & d
Answer:
(ii) b, c & d

Question 22.
DNA of mitochondrion is …………… .
(a) Helical
(b) Dumbbell
(c) Circular
(d) Spiral
Answer:
(c) Circular

Question 23.
Fluid droplets are engulfed by membrane, which form vesicles around them
a) Phagocytosis
b) Exocytosis
c) Endocytosis
d) Pinocytosis
Answer:
d) Pinocytosis

Question 24.
The 60 s large subunit of Eukaryotes contain
a) 23 s & 5 s – large subunit
b) 16 s r RNA in large subunit
c) 18 s r RNA in large subunit
d) 28 s, 5-8 sand 5 s in large subunit
Answer:
d) 28 s, 5-8 sand 5 s in large subunit

Question 25.
Elaioplasts store …………….
(a) Starch
(b) Lipid
(c) Protein
(d) Chlorophyll
Answer:
(b) Lipid

II. State whether the following statement True or False with reference to the origin of Eukaryotes.

1. A Prokaryote grow in size and develop infoldings in its cell membrane to increase surface area to volume ratio
2. Aerobic protea bacterium enter eukaryote as prey or parasite and become an endosymbiont
3. Proteobacteria eventually assimilated and became mitochondria
4.  Some Prokaryotes go on to acquire additional Exo symbionts the cyanobacteria evolve to become chloroplasts.

Answer:
b) True, True, True, False

Question 2.
Find out the true and false statements from the following and on that basis And the correct answer.
(i) In Prokaryotes the flagellar rotation, only proton movements are involved & not ATP.
(ii) In Eukaryotes to shift the adjacent microtubules to bend cilia or flagella, dynein use energy from ATP
(iii) Bacterial flagella are made up of helical polymers of protein known as Tubulin
(iv) In Eukaryotes the flagella are made up of microtubules and proteins known as dynein and nexin.

Answer:
b) True True False True

Question 3.
With reference to Eukaryotic flagellum Find out the true or false statements from the following and on that basis find the correct answer
(i) Flagellum is shorter than cilia as short as 200 µm
(ii) Flagella are microtubule projection of plasma membrane
(iii) Flagella composed of 8 pairs of microtubules with 2 pairs of microtubules in the center
(iv) Structure of Flagella has Axoneme made up of microtubules & protein tubules

Answer:
c) False True False True

Question 4.
(i) Cytoplasm is the physical basis of life
(ii) Cytoplasm inheritance occurs only through the plasma genes
(iii) Cytoplasm serves as a molecular soup where all the cellular organelles are suspended and bound together by a lipid bilayer plasma membrane
(iv) Cytoplasm is a very bad conductor of electricity.

Answer:
a) False True True False

Question 5.
Find out the true or false statements from the following and on that basis find the correct answer
(i) The contractibility of protoplasm is important for the absorption and removal of water, especially in stomatal operations
(ii) The viscosity of protoplasm is 2-20centipoises
(iii) The protoplasm is made of 10-20% of water
(iv) Brownian movement and Tyndall effect are colloidal properties, so not applicable to protoplasm

Answer:
d) True True False False

II. Choose The Wrong Match

Question 1.
(a) Cytoplith – Hypodermal leaf cells of ficus bengaliensis
(b) Raphides – Eichhomia leaves
(c) Sphaero raphides – Colocasia
(d) Silica – Oryza sativa
Answer:
d) Silica – Oryza sativa

Question 2.
Choose the wrong match with reference to mitochondria
(a) Protein – 73%
(b) Lipids – 25-30%
(c) DNA – 12%
(d) RNA – 5-7%
Answer:
c) DNA-12%

Question 3.
(i) Centrosome give rise to spindle fibers in Animal cell
(ii) Golgibodies play important role in packaging and secretion
(iii) Endoplasmic reticulum-SER is involved in protein synthesis
(iv) Vacuoles facilitate the transport of ions and materials in plant cell
Answer:
(iii) Endoplasmic reticulum SER is involved in protein synthesis

Question 4.
(i) The magnification of SEM & its resolving power is – 200000 &5-20nm
(ii) The magnification &resolution power of temis – 1 – 300000&2-10A
(iii) The magnification power of TEM is – 100000 then the light microscope
(iv) The magnification power of phase-contrast – 3 – 40000 & 8-10A microscope &its resolution power
Answer:
(iv) The magnification power contrast is microscope & its resolution power – 3-400000 & 8-10A

IV. Choose The Right Match From The Following

Question 1.
(i) Size of mycoplasma – 0.15-0.03 µm
(ii) Size of BGA – 60mm
(iii) Size of RBC – 0.25-0.06 µm
(iv) Size of chick egg – 7-811mm
Answer:
(i) Size of mycoplasma – 0.15-0.03µm

Question 2.
Choose the right match:
(i) Volutin granules occurin -Bacteria
(ii) Ttannin – Cassia auriculata
(iii) Calcium carbonate – Mimosa pudica
(iv) Heavy metals – Erchhornia
Answer:
(i) Volutin granules- Bacteria

Question 3.
Choose the right match:
(i) Cell theory – Cortix
(ii) Protoplasm theory – Max Schultze
(iii) Chromosomes physical carriers of genes – Strasburger
(iv) Endoplasmic reticulum word coined by – Benda
Answer:
(ii) Protoplasm theory – Max Schultze

V. Match The Following And Find The Correct Answer:

Question 1.
(i) Harry Beevers – (A) identified Lysosomes a Peroxisomes
(ii) Christian Do Duve – (B) Discovered Glycoxysome c
(iii) A-F-U- Schimper – (C) Coined the word Chromosome
(iv) Waldeyer – (D) Coined the word Plastids

Answer:
a) B A D C

Question 2.
(i) When the small pieces of golgibody pinches off from its tubules to form – A. Chioroplast
(ii) Fernandez moran particles occur in – B. Golgi apparatus
(iii) Zymogen granules occur in – C. Lysosome
(iv) Quantosomes are present in – D. Mitochondria

Answer:
b) C D B A

Question 1.
ASSERTION (A): A cell membrane shows fluid behavior
REASON (R): A membrane is- a mosaic or composite of diverse lipids and proteins
a) Assertion and Reason are correct ‘R’ explaining ‘A’
b) A and R-correct ‘R’ not explaining A
c) A is true, but R is wrong
d) A is true but R is not explaining A
Answer:
(a) Assertion A & Reason R are correct R is explaining A

Question 2.
Assertion (A): Chloroplast is an important cell organelle performing photosynthesis in plants
Reason (R): An organelle is a distinct part of a cell which has a particular structure and function.
a) A and R are correct R explaining A
b) A and R correct and R not explaining A
c) A is true, but R is wrong
d) A is true but R is not explaining A
Answer:
b) A and R correct R not explaining A

Question 3.
Assertion (A): The inheritance of Mitochondria is uniparental
Reason (R): Mitochondria of any one of the parenting divide and gets distributed to daughter cells.
a) A and R are correct R explaining A
b) A and R are correct R not explaining A
c) A is true but R is wrong
d) A is true but R is not explaining A
Answer:
(c) A is true but R is wrong

Question 4.
Assertion (A): The objective of optic lenses of a microscope are interchanged, then it can work as a telescope
Reason (R): The objective of the telescope has a small focal length
(a) A and R are correct R explaining A
(b) A and R are correct R not explaining A
(c) A is true but R is wrong
(d) A is true but R is not explaining A
Answer:
(d) A is true but R is not explaining A

Question 5.
Assertion (A): A polytene achieved by repeated replication of chromosomal DNA without nuclear division. The daughter chromatids aligned side by side called Endomitosis
Reason (R): Polytenes is observed in the salivary glands of Drosophila by C.G.Balbiani. 1881.
a) A and R are correct R explaining A
b) A and R are correct R not explaining A
c) A is true but R is wrong
d) A is true but R is not explaining A
Answer:
(b) A and R correct R not explaining A

Two Marks Questions

Question 1.
Name the scientist who proposed the cell theory.
Answer:
Matthias Schleiden and Theodor Schwann.

Question 2.
ER- can be referred to as the endoskeleton of the cell. Justify.
Answer:

• Yes. It connects plasma membrane & nuclear membrane, giving support to the Cytosol so we can call it the endoskeleton of the cell.
• It also helps in the exchange of substances in and out of the cell.

Question 3.
Why do we say that viruses are an exception to its cell theory?
Answer:
Viruses lack protoplasm, the essential parts of the cell, and are existing as obligate parasites (i.e)(subcellular particles).

Question 4.
Who said that different kinds of plastids can transform into one another?
Answer:

A-F-U Schimper said that the 3 different kinds of plastids can transform into one another according to the need or demand of the plant body.

Question 5.
In a Bright field microscope, where does the primary & secondary magnification occurs?
Answer:
Primary magnification is obtained through, objective lens, and secondary magnification is obtained through an eye piece lens.

Question 6.
State the functions of chloroplast
Answer:

• They are organs of Photosynthesis.
• Light reactions & dark reactions take place in the granum & stroma respectively.
• Chloroplast also play important role in the Photorespiration or C₂ cycle.

Question 7.
Distinguish between 70’s & 80’s Ribosomes.
Answer:

Question 8.
Name the types of cells based on nuclear characteristics.
Answer:
The types of cells based on nuclear characteristics:

1. Prokaryotes
2. Mesokaryotes and
3. Eukaryotes.

Question 9.
Distinguish between glyoxysomes, peroxysomes & sphaerosomes
Answer:

Question 10.
Distinguish between Resolution & Magnification:
Answer:

Question 11.
Differentiate 4 points of differences between Prokaryotes & Mesokaryotes
Answer:

Question 12.
Write down any 4 functions of cell wall
Answer:

Question 13.
Differentiate between TEM and SEM:
Answer:

Question 14.
Explain signal transduction:
Answer:
DEFINITION:

• It is a process by which a cell receives information from outside and respond to it is called signal transduction
• Nitric oxide → is the main signally molecule
• Cell membrane → site of chemical interaction of signal transduction

Question 15.
Draw the structure of the Golgi apparatus & label its parts.
Answer:

Question 16.
What is the cell wall composition of the following organism?
(a) Fungi
(b) Bacteria
(c) Algae
Answer:
(a) Fungi – Chitin and fungal cellulose.
(b) Bacteria – Peptidoglycan
(c) Algae – Cellulose, mannan and galactan.

Question 17.
What is meant by Holocentric chromosomes?
Answer:
If a chromosome has centromere activity distributed along the whole surface of the chromosome during mitosis (i.e) microtubules distributed all along the mitotic chromosome.
Eg. Caenorhabditis Elegans (transparent nematode) & many insects.

Question 18.
Differentiate between point centromere & Regional centromere.
Answer:

Question 19.
Draw the structure of the polytene chromosome:
Answer:

Question 20.
Draw the structure of the lysosome.
Answer:

Three Mark Questions

Question 1.
Distinguish between autosomes & allosomes.
Answer:

Question 2.
Explain lampbrush chromosomes:
Answer:

• In 1882- observed by Flemming in Oocytes of animal Salamander &Giant nucleus of unicellular Algae Acetabularia
• The highly condensed chromosomes form a chromosomal axis, from which lateral loops of DNA formed as a result of intense RNA synthesis

Question 3.
Define cytoplasmic streaming.
Answer:
Cytoplasmic streaming refers to the movement of the cytoplasm along with the cellular materials inside the cell.

Question 4.
Draw the structure of the Eukaryotic flagellum.
Answer:

Question 5.
List out the functions of the Cell Wall.
Answer:
The cell wall plays a vital role in holding several important functions given below.

1. Offers definite shape and rigidity to the cell.
2. Serves as barrier for several molecules to enter the cells.
3. Provides protection to the internal protoplasm against mechanical injury.
4. Prevents the bursting of cells by maintaining the osmotic pressure.
5. Plays a major role by acting as a mechanism of defense for the cells.

Question 6.
Explain in detail about Fluid mosaic model.
Answer:
Jonathan Singer and Garth Nicolson (1972) proposed fluid model: It is made up of lipids and proteins together with a little amount of carbohydrate. The lipid membrane is made up of phospholipid. The phospholipid molecule has a hydrophobic tail and hydrophilic head. The hydrophobic tail repels water and water-loving polar molecule are called hydrophilic molecule. They have polar phosphate group responsible for attracting water. Water-hating non – polar molecule are called as a hydrophobic molecules. They have fatty acid which is non – polar which cannot attract water.

Hydrophilic head attracts water. The proteins of the membrane are globular proteins which are found intermingled between the lipid bilayer most of which are projecting beyond the lipid bilayer. These proteins are called as integral proteins. Few are superficially attached on either surface of the lipid bilayer which are called as peripheral proteins. The proteins are involved in the transport of molecules across the membranes and also act as enzymes, receptors or antigens.

Question 7.
Draw the structure of the chromosome & neatly label the parts:
Answer:

Question 8.
Based on the position of centromere classify the chromosomes with the help of diagrams.
Answer:

Eukaryotic chromosomes may be rod-shaped telo & acrocentric as well as meta & sub-meta-centric.

Question 9.
List out the functions of Golgi bodies.
Answer:
Functions of Golgi bodies:

1. Glycoproteins and glycolipids are produced.
2. Transporting and storing lipids.
3. Formation of lysosomes.
4. Production of digestive enzymes.
5. Cell plate and cell wall formation
6. Secretion of carbohydrates for the formation of plant cell walls and insect cuticles.
7. Zymogen granules (proenzyme / pre-cursor of all enzymes) are synthesized.

Question 10.
Explain the structure of Cilia.
Answer:

• Short cellular-numerous microtubule bound projections of plasma membrane.
• Each Cilium has membrane-bound structures, basal body,rootlets, basal plate shaft
• Shaft (axoneme) consists of nine pairs of microtubule doublets, arranged in a
• circle along the periphery with a two central tubules (9+2) arrangement of microtubules is present.
• Microtubules – made up of tubulin.
• Motor protein dynein – connects the outer microtubules pair & links them to the central pair.
• Nexin – links the peripheral doublets of microtubules.

Question 11.
Write in detail about the 3 types of centromere in eukaryotes.
Answer:
There are three types of centromere in Eukaryotes. They are as follows:

1. Point Centromere: The type of centromere in which the kinetochore is assembled as a result of protein recognition of specific DNA sequences. Kinetochores assembled on point centromere bind a single microtubule. It is also called a localized centromere. It occurs in budding yeasts.
2. Regional Centromere: In regional centromere where the kinetochore is assembled on a variable array of repeated DNA sequences. Kinetochore assembled on regional centromeres bind multiple microtubules. It occurs in fission yeast cell, humans and so on.
3. Holocentromere: The microtubules bind all along the mitotic chromosome. Example: Caenorhabditis Elegans (transparent nematode) and many insects.

Question 12.
Distinguish between primary wall & secondary wall of the plant cell wall.
Answer:

Question 13.
Describe the steps involved in cytological techniques.
Answer:
There are different types of mounting based on the portion of a specimen to be observed.

1. Whole-mount: The whole organism or smaller structure is mounted over a slide and observed.
2. Squash: This is a preparation where the material to be observed is crushed/squashed onto a slide so as to reveal its contents. Example: Pollen grains, mitosis, and meiosis in root tips and flower buds to observe chromosomes.
3. Smears: Here the specimen is in the fluid (blood and microbial cultures etc) are scraped, brushed, or aspirated from the surface of the organ. Example: Epithelial cells.
4. Sections: Freehand sections from a specimen and thin sections are selected, stained, and mounted on a slide. Example: Leaf and stem of plants.

Question 14.
List out any 3 stains used in histo- chemistry.
Answer:

Question 15.
Identify the diagram and label the parts.

Answer:
This is a dark field microscope
A-objective lens
B-stage
C-condenser lens
D- patch stop
E-light source

Five Mark Questions

Question 1.
Differentiate between BFM & DFM.
Answer:

Question 2.
Differentiate between Light microscope & electron microscope.
Answer:

Question 3.
Write down the functions of the cell wall.
Answer:

Question 4.
Write down the functions of the Plasma Membrane or cell membrane.
Answer:

• Cell transport is the main function
• PM act as a channel of transport for molecules
• PM is selectively permeable to molecules

It transported by

1. Energy-dependent processes,
2. Energy independent processes Membrane proteins involved processes
3. Endocytosis & Exocytosis large quantity of solids and liquids are transported into a cell or out of cells.

I. Endocytosis 2 types
a) Phagocytosis particle is engulfed by membrance which fold around it forming vesicles, enzymes digest and products are absorbed.

b) Pinocytosis Fluid droplets are engulfed by forming vesicles.
II. Exocytosis -Vesicles fuse with the plasma membrane and eject contents.
-This may be a secretion in the case of digestive enzymes hormones or mucus.

Question 5.
Explain the fluid mosaic model of plasma membrane.
Answer:

• Jonathan Singer & Garth Nicolson (1972) proposed FM model.
• Plasma membrane made up of lipid (phospholipid), protein & little carbohydrate.

I. Phospholipid: Molecule has a hydrophobic tail(repel water) & hydrophilic head (water-loving)
II. Protein of membrane

• Globular in nature intermingles between lipid bipolar most perfect beyond Jt known
  as (integral proteins)

Few are superficially attached on either surface of lipid bilayer (peripheral proteins)

• They are involved in transport of molecules across the membrane
• They acts as enzymes
• They acts as receptors or antigens.

III Carbohydrate

• They are short chain of polysaccharides.
  (i.e) With protein glycoprotein With lipid glycolipids, glycocalyx

Flip Flapping:

• The movement of membrane lipids from one side of the membrane to the other side by vertical movement called flip-flap movement.

Answer:
A- hydrolipid tail,
B-hydrophilic head,} lipid
C-intrisic protein
D-extrinsic protein
This movement is very slow than lateral diffusion of lipid molecules.

• Phospholipids can flip flop due to smaller polar regions.
• Proteins cannot do so because of extensive polar regions.

Question 6.
Give an account of the structure and function of mitochondria.
Answer:

• 1st observed by A. Kolliker (1880)
• Altmann(1894) – named it as Bio-plasts
• Benda (1897) – named as Mitochondria

Structure

• Ovoid, rod-shaped, pleomorphic structures
• Double membrane
• Outer membrane smooth, & permeable- contain porins

2 compartments
1. outer chamber between 2 membranes
2. Inner chamber filled with matrix

Cristae – Infoldings of inner membrane:

• It contain enzymes for ETS(Electron Transport System)
• Inner membrane has FI particles or exosomes
• Each FI particle has a base, a stem & a rounded head
• Head has ATP synthetase to do oxidative phosphorylation content.
  • 73% protein
  • 25-30% lipids
  • 5-7% RNA, DNA & enzymes(about 60 circular DNA &70’s Ribosomes.
• All enzymes of Kreb’s cycle are found in the matrix except succinate dehydrogenase.
• Mitochondria is a semi-autonomous body
• It’s inheritance is uniparental (i.e) maternal
• It is used to track recent evolutionary time because it mutates 5-10 times faster than DNA in the nucleus.

Question 7.
Structure of chloroplast
Answer:

• A vital organ of green plants.
• Double membrane-bound organelle peripheral space in between the membrane
• Inner chloroplast is filled with gelatinous stroma
• Inside the stroma interconnected sacs called Thylakoids
• Inner space of the thylakoid is the thylakoid lumen
• Thylakoids stacked together like piles of coins known as grana.
• Light is absorbed and converted into chemical energy (carbohydrates) in the granum
  
• Chloroplast genome encodes for approximately 30 proteins involved in photosystem I & II – cytochrome, b, f, complex and ATP synthase & also one of the subunits of RUBISCO is enclosed by it.
• RUBISCO- is the major protein component of the stroma single most abundant protein on earth
• The thylakoid contain small, rounded photosynthetic units called Quantosomes
• The chloroplast is semi-autonomous, divided by fission.
  

Question 8.
Give an account of Ribosomes:
Answer:

• 1953 – 1 observed by George Palade
• Dense particles in the EM not membrane-bound

Electron microscope observation
1. Made up of 2 round subunits one large layer & one small unit to form a complete unit
2. Mg++ is required for complete cohesion.
Biogenesis – denova formation, auto replication and nucleolar origin
Function – Sites of protein synthesis.

Content – consists of

• RNA 60%,
• Protein 40%

Polysemes:
In protein synthesizing cells, many ribosomes attached to single m RNA – to form polysomes’ main role in the formation of several copies of particular.

Question 9.
Differentiate between chromoplast & leucoplast
Answer:

Question 10.
State any 3 functions of Lysosomes
Answer:
polypeptide Intracellular digestion:
They digest carbohydrates, proteins & lipids present in the cytoplasm

Autophagy:
During the adverse condition, they digest their own organelles like mitochondria ER

Auto lysis:
Causes self-destruction of cell on the insight of disease

Aging:
Have autolytic enzymes that disrupts intracellular molecules.

Question 11.
Explain the structure of Centrioles
Answer:

• Central hub, surrounded by nine triplet peripheral fibrils (tubulin) connected to the tubules by radial spokes (9 + 0) pattern Cilia or Flagella Spindle fibres
• Centriole is the basal body of Flagella, Lilia or, Spindle fibers.
• It is a nonmembranous organelle

Question 12.
Differentiate between other inclusions of cells in Prokaryotes & Eukaryotes.
Answer:

Question 13.
Explain the structure of the Nucleus.

• It is important CPU of the cell, the largest part of it
• Control all activities of cell
• Hold the hereditary information

Nuclear envelope Nuclear space (nucleoplasm)

I Membrane:
Double membrane Nuclear envelope
a) Outer membrane

• Rough by the presence of ribosomes and with irregular intervals continues with ER
• It has nuclear pores that allow m RNA, ribosomal units, proteins & other macromolecules to pass in & out
• Nuclear pore enclosed by circular structure – annuli

b) Inner membrane:
Smooth without ribosomes in between the two membranes perinuclear space is present

II. Nucleoplasm:
A gelatinous matrix has 2 parts

• Nucleoli &
• Chromatin reticulum

a) Nucleoli:

• Small dense spherical structure occur in singly or in multiples.
• It possesses genes for r RNA &, tRNA

b) Chromatin network

• Uncoiled, indistinct , thread like structure(inter phase)
• Has little amount of RNA, DNA bound to histone proteins in Eukaryotes
• At the time of cell division – It get condensed to form Chromosome

Euchromatin With -2 parts
1. Euchromatin
2.Heterochromatin

• The portion that get transcribed into rn RNA – active genes that are not tightly condensed & stains lightly.
• Heterochromatin
• The portion of chromatin that does not get transcribed into m RNA – remain tightly condensed & stains intensively.

Question 14.
Explain the structure of Endoplasmic reticulum
Answer:

• The largest internal membrane (ER)
• Name given by K.R.Porter(1948)
  Consists of Vesicles &Tubules, Cisternae

Cisternae:

• Long broad, flat sac-like structures arranged in stacks to form lamella.
• In between membrane is filled with fluid

Vesicles:
Oval membrane-bound vascular structure

Tubules:
Irregular shaped, branched, smooth-walled structure enclosing a space

Function:

• It is associated with nuclear membrane and cell surface membrane
• When ribosomes present on ER- it is known as (RER) Rough Endoplasmic Reticulum
• When ribosomes absent on ER- it is known as Smooth Endoplasmic Retiöulum(SER).

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Chemistry Guide Pdf Chapter 3 Periodic Classification of Elements Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Chemistry Solutions Chapter 3 Periodic Classification of Elements

11th Chemistry Guide Periodic Classification of Elements Text Book Back Questions and Answers

Textual Questions:

I. Choose the best Answer:

Question 1.
What would be the IUPAC name for an element with atomic number 222?
(a) bibibiium
(b) bididium
(c) didibium
(d) bibibium
Answer:
(d) bibibium

Question 2.
The electronic configuration of the elements A and B are 1s², 2s², 2p⁶, 3s² and 1s², 2s², 2p⁵ respectively. The formula of the ionic compound that can be formed between these elements is
(a) AB
(b) AB₂
(c) A₂B
(d) none of the above
Answer:
(b) AB₂

Question 3.
The group of elements in which the differentiating electron enters the anti penultimate shell of atoms are called
(a) p-block elements
(b) d-block elements
(c) s-block elements
(d) f-block elements
Answer:
(d) f-block elements

Question 4.
In which of the following options the order of arrangement does not agree with the variation of property indicated against it?
(a) I < Br < Cl < F (increasing electron gain enthalpy)
(b) Li < Na < K < Rb (increasing metallic radius)
(c) Al³⁺ < Mg²⁺ < Na⁺ < F^– (increasing ionic size)
(d) B < C < O < N (increasing first ionisation enthalpy)
Answer:
(a) I < Br < Cl < F (increasing electron gain enthalpy)

Question 5.
Which of the following elements will have the highest electronegativity?
(a) Chlorine
(b) Nitrogen
(c) Cesium
(d) Fluorine
Answer:
(d) Fluorine

Question 6.
Various successive ionisation enthalpies (in kjmol 1) of an element are given below.

The element is
(a) phosphorus
(b) Sodium
(c) Aluminium
(d) Silicon
Answer:
(c) Aluminium

Question 7.
In the third period the first ionization potential is of the order.
(a) Na > Al > Mg > Si > P
(b) Na < Al < Mg < Si < P
(c) Mg > Na > Si > P > Al
(d) Na < Al < Mg < P < Si
Answer:
(b) Na < Al < Mg < Si < P

Question 8.
Identify the wrong statement.
(a) Amongst the isoelectronic species, smaller the positive charge on cation, smaller is the ionic radius
(b) Amongst isoelectric species greater the negative charge on the anion, larger is the ionic radius
(c) Atomic radius of the elements increases as one moves down the first group of the periodic table
(d) Atomic radius of the elements decreases as one moves across from left to right in the 2nd period of the periodic table.
Answer:
(a) Amongst the isoelectronic species, smaller the positive charge on cation, smaller is the ionic radius

Question 9.
Which one of the following arrangements represent the correct order of least negative to most negative electron gain enthalpy
(a) Al < O < C < Ca < F
(b) Al < Ca < O < C < F
(c) C < F < O < Al < Ca
(d) Ca < Al < C < O < F
Answer:
(d) Ca < Al < C < O < F

Question 10.
The correct order of electron gain enthalpy with negative sign of F, Cl, Br and I having atomic number 9, 17, 35 and 53 respectively is
(a) I > Br > Cl > F
(b) F > Cl > Br > I
(c) Cl > F > Br > I
(d) Br > I > Cl > F
Answer:
(c) Cl > F > Br > I

Question 11.
Which one of the following is the least electronegative element?
(a) Bromine
(b) Chlorine
(c) Iodine
(d) Hydrogen
Answer:
(d) Hydrogen

Question 12.
The element with positive electron gain enthalpy is
(a) Hydrogen
(b) Sodium
(c) Argon
(d) Fluorine
Answer:
(c) Argon

Question 13.
The correct order of decreasing electronegativity values among the elements X, Y, Z and A with atomic numbers 4, 8, 7 and 12 respectively
(a) Y > Z > X > A
(b) Z > A > Y > X
(c) X > Y > Z > A
(d) X > Y > A > Z
Answer:
(a) Y > Z > X > A

Question 14.
Assertion:
Helium has the highest value of ionisation energy among all the elements known
Reason:
Helium has the highest value of electron affinity among all the elements known
(a) Both assertion and reason are true and reason is correct explanation for the assertion
(b) Both assertion and reason are true but the reason is not the correct explanation for the assertion
(c) Assertion is true and the reason is false
(d) Both assertion and the reason are false
Answer:
(c) Assertion is true and the reason is false

Question 15.
The electronic configuration of the atom having | maximum difference in first and second ionisation j energies is
(a) 1s², 2s², 2p⁶, 3s¹
(b) 1s², 2s², 2p⁶, 3S²
(c) 1s², 2s², 2p⁶, 3s², 3s², 3p⁶, 4s¹
(d) 1s², 2s², 2p⁶, 3s², 3p¹
Answer:
(a) 1s², 2s², 2p⁶, 3s¹

Question 16.
Which of the following is second most electronegative element?
(a) Chlorine
(b) Fluorine
(c) Oxygen
(d) Sulphur
Answer:
(a) Chlorine

Question 17.
IE₁ and IE₂ of Mg are 179 and 348 kcal mol^-1 respectively. The energy required for the reaction Mg → Mg²⁺ + 2e^– is
(a) + 169 kcal mol^-1
(b) -169 kcal mol^-1
(c) +527 kcalmol^-1
(d) -527 kcal mol^-1
Answer:
(c) +527 kcalmol^-1

Question 18.
In a given shell the order of screening effect is
(a) s > p > d > f
(b) s > p > f > d
(c) f > d > p > s
(d) f > p > s > d
Answer:
(a) s > p > d > f

Question 19.
Which of the following orders of ionic radii is correct?
(a) H > H⁺ > H
(b) Na⁺ > F^– > O^2-
(c) F > O^2- > Na⁺
(d) None of these
Answer:
(d) None of these

Question 20.
The First ionisation potential of Na, Mg and Si are 496, 737 and 786 kJ mol^-1 respectively. The ionisation potential of Al will be closer to
(a) 760 kJ mol^-1
(b) 575 kJ mol^-1
(c) 801 kJ mol^-1
(d) 419 kJ mol^-1
Answer:
(b) 575 kJ mol^-1

Question 21.
Which one of the following is true about metallic character when we move from left to right in a period and top to bottom in a group?
(a) Decreases in a period and increases along the group
(b) Increases in a period and decreases in a group
(c) Increases both in the period and the group
(d) Decreases both in the period and in the group
Answer:
(b) Increases in a period and decreases in a group

Question 22.
How does electron affinity change when we move from left to right in a period in the periodic table?
(a) Generally increases
(b) Generally decreases
(c) Remains unchanged
(d) First increases and then decreases
Answer:
(a) Generally increases

Question 23.
Which of the following pairs of elements exhibit diagonal relationship?
(a) Be and Mg
(b) Li and Mg
(c) Be and B
(d) Be and Al
Answer:
(d) Be and Al

II. Write brief answer to the following questions:

Question 24.
Define modern periodic law.
Answer:
The modem periodic law states that “The physical and chemical properties of the elements are a periodic function of their atomic numbers.”

Question 25.
What are isoelectronic ions? Give examples.
Answer:
Two ions having the same number of electrons are called isoelectronic ions.
Example: Na⁺ (1s² 2s² 2p⁶) and F^– (1s² 2s² 2p⁶). Both these ions contain eight electrons.

Question 26.
What is an effective nuclear charge?
Answer:
The net nuclear charge experienced by valence electrons in the outermost shell is called the effective nuclear charge.
Z_eff = Z – S
Where Z = Atomic number
S = Screening constant calculated by using Slater’s rules.

Question 27.
Is the definition given below for ionization enthalpy is correct?
Answer:
“Ionisation enthalpy is defined as the energy required to remove the most loosely bound electron from the valence shell of an atom”
The given statement is not correct. Ionization energy is defined as the minimum amount of energy required to remove the most loosely bound electron from the valence shell of the isolated neutral gaseous atom in its ground state.

Question 28.
Magnesium loses electrons successively to form Mg⁺, Mg^2+, and Mg³ ions. Which step will have the highest ionization energy and why?
Answer:
Magnesium loses electrons successively in the following steps,
Step 1:
Mg_(g) + IE₁ → Mg⁺_(g) + 1e, Ionisation energy = I.E₁
Step 2:
Mg⁺_(g)+ IE₂ → Mg²⁺_(g) + 1e, Ionisation energy = I.E₂
Step 3:
Mg²⁺_(g) + IE₃ → Mg³⁺_(g) + 1e, Ionisation energy = I.E₃
The total number of electrons is less in the cation than the neutral atom while the nuclear charge remains the same. Therefore, the effective nuclear charge of the cation is higher than the corresponding neutral atom. Thus, the successive ionization energies, always increase in the following order I.E₁ < I.E₂ < I.E₃. Thus, Step-3 will have the ionization energy.

Question 29.
Define electronegativity.
Answer:
Electronegativity is defined as the relative tendency of an element present in a covalently bonded molecule, to attract the shared pair of electrons towards itself.

Question 30.
How would you explain the fact that the second ionisation potential is always higher than the first ionisation potential?
Answer:

• The second ionization potential is always higher than the first ionization potential.
• Removal of one electron from the valence orbit of a neutral gaseous atom is easy so first ionization energy is less. But from a uni positive ion, removal of one more electron becomes difficult due to the more forces of attraction between the excess of protons and less number of electrons.
• Due to greater nuclear attraction, second ionization energy is higher than first ionization energy.

Question 31.
The energy of an electron in the ground state of the hydrogen atom is -2.8 × 10^-8 J. Calculate the ionization enthalpy of atomic hydrogen in terms of kJ mol^-1
Answer:
Energy of an electron in the ground state of the hydrogen atom is – 2.8 × 10^-8.
The ionization energy of atomic hydrogen is 2.8 × 10^-18 × 6.023 × 10²³ J/mol
= 16.86 × 10⁵ J/mol
= 1686 kJ/mol.

Question 32.
The electronic configuration of an atom is one of the important factors which affects the value of ionization potential and electron gain enthalpy. Explain.
Answer:

• The electronic configuration of an atom affects the value of ionization potential and electron gain enthalpy.
• Half-filled valence shell electronic configuration and completely filled valence shell electronic configuration are more stable than partially filled electronic configuration.
• For e.g. Beryllium (Z = 4) 1s² 2s² (completely filled electronic configuration)
  Nitrogen (Z = 7) 1s²  2s²  2p_x¹  2p_y¹ 2p_z¹ (half-filled electronic configuration) Both beryllium and nitrogen have high ionization energy due to more stable nature.
• In the case of beryllium (1s² 2s²), nitrogen (1s² 2s² 2p³) the addition of extra electrons will disturb their stable electronic configuration and they have almost zero electron affinity.
• Noble gases have stable ns² np⁶ configuration and the addition of further electrons is unfavorable and they have zero electron affinity.

Question 33.
In what period and group will an element with Z = 118 will be present?
Answer:
The element Ununoctium (Oganesson, Z – 118) present in the 7^th period and 18^th group of the periodic table.

Question 34.
Justify that the fifth period of the periodic table should have 18 elements on the basis of quantum numbers.
Answer:
The fifth period of the periodic table has 18 elements. 5^th period starts from Rb to Xe (18 elements).
5^th period starts with principal quantum number n = 5 and l = 0, 1, 2, 3 and 4.
When n = 5, the number of orbitals = 9.
1 for 5s
5 for 4d
3 for 5p
The total number of orbitals = 9.
Total number of electrons that can be accommodated in 9 orbitals = 9 x 2 = 18.
Hence the number of elements in the 5th period is 18.

Question 35.
Elements a, b, c and d have the following electronic configurations:
a: 1s², 2s², 2p⁶
b: 1s², 2s², 2p⁶, 3s², 3p¹
c: 1s², 2s², 2p⁶, 3s², 3p⁶
d: 1s², 2s², 2p¹
Which elements among these will belong to the same group of the periodic table?
Answer:
The elements ‘a’ [Ne (Z= 10), 1s², 2s², 2p⁶] and ‘c’ [Ar (Z = 18), 1s², 2s², 2p⁶, 3s², 3p⁶] have the same valence electronic configuration and hence, belongs to the same group, i.e., group 18 of the periodic table . Similarly, the elements ‘b’ [ Al (Z = 13), 1s², 2s², 2p⁶, 3s², 3p¹] and ‘d’ [B (Z= 5), 1s², 2s², 2p¹] have the same valence electronic configuration and hence, belongs to the same group, i.e., group 13 of the periodic table.

Question 36.
Give the general electronic configuration of lanthanides and actinides?
Answer:

• The electronic configuration of lanthanides is 4f^1-14 5d^0-16s².
• The electronic configuration of actinides is 5f^1-14 6d^0-1 7s².

Question 37.
Why do halogens act as oxidizing agents?
Answer:
Halogens are having the general electronic configuration of ns², np⁵ and readily accept an electron to get the stable noble gas electronic configuration. Therefore, halogens have high electron affinity. Hence, halogens act as oxidizing agents.

Question 38.
Mention any two anomalous properties of second-period elements.
Answer:

• In the 1^st group, lithium forms compounds with more covalent character while the other elements of this group form only ionic compounds.
• In the 2^nd group, beryllium forms compounds with more covalent character while the other elements of this family form only ionic compounds.

Question 39.
Explain the Pauling method for the determination of ionic radius.
Answer:
Ionic radius is defined as the distance from the centre of the nucleus of the ion upto which it exerts its influence on the electron cloud of the ion. The ionic radius of a uni-univalent crystal can be calculated using Pauling’s method from the interionic distance between the nuclei of the cation and anion. Pauling assumed that ions present in a crystal lattice are perfect spheres, and they are in contact with each other and therefore,
d = r_c+ + r_A- …………..(1)
where ‘d’ is the distance between the centre of the nucleus of the cation C⁺ and A^–. r ^c+ and r^A- are the radius of the cation and anion respectively.

Pauling also assumed that the radius of the ion having noble gas electronic configuration (Na⁺ and Cl^– having 1s², 2s², 2p⁶ configuration) is inversely
proportional to the effective nuclear charge felt at the periphery of the ion.
i.e.,   r_c+ ∝ \(\frac{1}{\left(Z_{e f f}\right)^{C+}}\) ………(2)

and r_A- ∝ \(\frac{1}{\left(Z_{e f f}\right)^{A-}}\) ………….(3)

where Z_eff is the effective nuclear charge.
Z_eff = Z – S.
Dividing the equation (2) by (3)
\(\frac{r_{c^{+}}}{r_{A^{-}}}=\frac{\left(Z_{e f f}\right)^{A-}}{\left(Z_{e f f}\right)^{C+}}\)

On solving the equations (1) and (4), the ionic radius of cation and anion are calculated.

Question 40.
Explain the periodic trend of ionisation potential.
Answer:
(a) The energy required to remove the most loosely held electron from an isolated gaseous atom is called ionization energy.
(b) Variation in a period:
Ionization energy is a periodic property. On moving across a period from left to right, the ionization enthalpy value increases. This is due to the following reasons.

• Increase of nuclear charge in a period
• Decrease of atomic size in a period

Because of these reasons, the valence electrons are held more tightly by the nucleus. Therefore, ionization enthalpy increases.

(c) Variation in a group:
As we move from top to bottom along a group, the ionization enthalpy decreases. This is due to the following reasons.

• A gradual increase in atomic size
• Increase of screening effect on the outermost electrons due to the increase of the number of inner electrons.

Hence, ionization enthalpy is a periodic property.

Question 41.
Explain the diagonal relationship.
Answer:
On moving diagonally across the periodic table, the second and third-period elements show certain similarities. Even though the similarity is not the same as we see in a group, it is quite pronounced in the following pair of elements.

The similarity in properties existing between the diagonally placed elements is called ‘diagonal relationship’.

Question 42.
Why the first Ionisation enthalpy of sodium is lower than that of magnesium while its second ionisation enthalpy Is higher than that of magnesium?
Answer:
The 1st ionization enthalpy of magnesium is higher than that of Na due to the higher nuclear charge and slightly smaller atomic radius of Mg than Na. After the loss of the first electron, Na⁺ formed has the electronic configuration of neon (2, 8). The higher stability of the completely filled noble gas configuration leads to a very high second ionization enthalpy for sodium. On the other hand, Mg⁺ formed after losing the first electron still has one more electron in its outermost (3s) orbital. As a result, the second ionization enthalpy of magnesium is much smaller than that of sodium.

Question 43.
By using Pauling’s method calculate the ionic radii of K⁺ and Cl^– ions in the potassium chloride crystal. Given that d^K + – Cl^– = 3.14 Å.
Answer:
d = r_K+ + r_Cl- = 3.14 Å
\(\frac{r_{K+}}{r_{C l-}}=\frac{\left(Z_{e f f}\right)^{C l-}}{\left(Z_{e f f}\right)^{K+}}\)

(Z_eff)^Cl- = Z – S = 17 – 10.9 = 6.1
(Z_eff)^K+ = Z – S = 19 – 16.8 = 2.2
\(\frac{r_{K+}}{r_{C l-}}=\frac{6.1}{2.2}\) = 2.77

r_K+ = 2.77 r_Cl-
2.77 r_Cl- + r_Cl- = 3.17 Å
3.77 r_Cl- = 3.17 Å
r_Cl- = 0.83 Å
r_K+ = (3.14 – 0.83) Å = 2.31 Å
The ionic radius of the K⁺ ion is 2.31 Å and Cl^– ion is 0.83 Å.

Question 44.
Explain the following, give appropriate reasons.
(i) Ionisation potential of N is greater than that of O:
Answer:
Nitrogen with 1s², 2s², 2p³ electronic configuration has higher ionization energy than oxygen. Since the half-filled electronic configuration is more stable, it requires higher energy to remove an electron from the 2p orbital of nitrogen. Whereas the removal of one 2p electron from oxygen leads to a stable half-filled configuration. This makes it comparatively easier to remove 2p electron from oxygen.

(ii) First ionisation potential of the C-atom is greater than that of the B atom, whereas the reverse is true is for the second ionisation potential.
Answer:
The first ionization potential of the C atom and B-atom are as follows:
C(1s², 2s², 2p²) + IE₁ → C⁺ (1s², 2s², 2p¹)

B(1s², 2s², 2p¹) + IE₁ → B⁺ (1s², 2s²)

The ionization energy usually increases along a period. Hence, the first ionization energy of carbon is greater than that of Boron.
The second ionization potential of the C atom and B atom is as follows:
C⁺ (1s², 2s², 2p¹) + IE₂ → C⁺(1s², 2s²)
B⁺ (1s², 2s²) + IE₂ → B⁺ (1s², 2s¹)

B⁺ has completely filled 2s orbital which is more stable than the partially filled valence shell electronic configuration of the C⁺ atom. Hence, the second ionization energy of Boron is greater than that of carbon.

(iii) The electron affinity values of Be, Mg, and noble gases are zero, and those of N (0.02 eV) and P (0.80 eV) are very low.
Answer:
Be, Mg and noble gases have completely filled stable configuration and the addition of further electron is unfavourable and requires energy. The addition of extra electrons will disturb their stable electronic configuration and hence, they have almost zero electron affinity.

Nitrogen and Phosphorus have a half-filled stable configurations and the addition of further electrons is unfavourable and requires energy. The addition of extra electrons will disturb their stable electronic configuration and hence, they have very low zero electron affinity.

(iv) The formation of from F^–_(g)  from F(g) is exothermic while that of O^2-_(g) from O(g) is endothermic.
Answer:
The sizes of oxygen and fluorine atoms are comparatively small and they have high electron density. The extra electron added to fluorine has to accommodate in the 2p orbital which is relatively compact. Hence, the formation of F- from F is exothermic. In the case of oxygen, the formation of O^2- from O is endothermic due to extra stability of the completely filled 2p orbital of O^2- formation.

Question 45.
What is the screening effect?
Answer:
The repulsive force between inner shell electrons and the valence electrons leads to a decrease in the electrostatic attractive forces acting on the valence electrons by the nucleus. Thus the inner shell electrons act as a shield between the nucleus and the valence electrons. This effect is called the shielding effect (or) screening effect.

Question 46.
Briefly give the basis for Pauling’s scale of electronegativity.
Answer:
Pauling’s scale:

• Electronegativity is the relative tendency of an element present in a covalently bonded molecule to attract the shared pair of electrons towards itself.
• Pauling assigned arbitrary values of electronegativities for hydrogen and fluorine as 2.2 and 4, respectively.
• Based on this the electronegativity values for other elements can be calculated using the following expression.
  (X_A-X_B) = 0.182 √E_AB – (E_AA E_BB)
  Where E_AB , E_AA, and E_BB are the bond dissociation energies of AB, A_2, and B₂ molecules respectively.
  X_A and X_B are electronegativity values of A and B.

Question 47.
State the trends in the variation of electronegativity in groups and periods.
Answer:
Variation of Electronegativity in a period:
The electronegativity generally increases across a period from left to right. As discussed earlier, the atomic radius decreases in a period, as the attraction between the valence electron and the nucleus increases. Hence, the tendency to attract shared pair of electrons increases. Therefore, electronegativity also increases in a period.

Variation of Electronegativity in a group:
The electronegativity generally decreases down a group. As we move down a group, the atomic radius increases, and the nuclear attractive force on the valence electron decreases. Hence, the electronegativity decreases. Noble gases are assigned zero electronegativity. The electronegativity values of the elements of 5-block show the expected decreasing order in a group. Except for 13^th and 14^th groups, all other p-block elements follow the expected decreasing trend in electronegativity.

11th Chemistry Guide Periodic Classification of Elements Additional Questions and Answers

I. Very Short Question and Answers (2 Marks):

Question 1.
State periodic law.
Answer:
Periodic law states that ‘‘the properties of the elements are the periodic functions of their atomic weights”.

Question 2.
Write a note about Chancourtois classification.
Answer:
In this system, elements that differed from each other in atomic weight by 16 or multiples of 16 fell very nearly on the same vertical line. Elements lying directly under each other showed a definite similarity. This was the first periodic law.

Question 3.
What is Lavoiser’s classification of elements?
Answer:
Lavoiser classified the substances into four groups of elements namely acid-making elements, gas-like elements, metallic elements, and earthy elements.

Question 4.
State Mendeleev’s periodic law.
Answer:
This law states that “The physical and chemical properties of elements are a periodic function of their atomic weights.”

Question 5.
What are groups and periods?
Answer:
All the elements are arranged in the modem periodic table which contains 18 vertical columns and 7 horizontal rows. In the periodic table, the vertical columns are called groups, and horizontal rows are called periods.

Question 6.
State modern periodic law.
Answer:
The modem periodic law states that, “The physical and chemical properties of the elements are periodic function of their atomic numbers.”

Question 7.
What are p-block elements? Give their general electronic configuration.
Answer:
The elements of groups 13 to 18 are called p-block elements or representative elements and have a general electronic configuration ns², np^{1 – 6}.

Question 8.
Mention the names of the elements with atomic numbers 101, 102, 109, and 110.
Answer:
Z = 101  IUPAC  name : Mendelevium
Z = 102  IUPAC  name : Nobelium
Z = 109  IUPAC  name : Meitnerium
Z = 110  IUPAC  name : Darmstadtium

Question 9.
What are f-block elements? Give their properties.
Answer:
The lanthanides and the actinides are called f-block elements. These elements are metallic in nature and have high melting points. Their compounds are mostly coloured. These elements also show variable oxidation states.

Question 10.
Give the name and electronic configuration of elements of group and 2 groups.
Answer:

• Elements of 1^st group are called alkali metals. Their electronic configuration is ns¹.
• Elements of 2^nd group are called alkaline earth metals. Their electronic configuration is ns².

Question 11.
Define Atomic radius.
Answer:
The atomic radius of an atom is defined as the distance between the centre of its nucleus and the outermost shell containing the valence electron.

Question 12.
Write any two characteristic properties of alkaline earth metals.
Answer:

• Alkaline earth metals readily lose their outermost electrons to form a +2 ion.
• As we go down the group. their metallic character and reactivity are increased.

Question 13.
Why is the covalent radius shorter than the actual atomic radius?
Answer:
The formation of a covalent bond involves the overlapping of atomic orbitals and it reduces the expected internuclear distance. Therefore, the covalent radius is always shorter than the actual atomic radius.

Question 14.
Define metallic radius.
Answer:
Metallic radius is defined as one-half of the distance between two adjacent metal atoms in the closely packed metallic crystal lattice.

Question 15.
Halogens and chalcogens have highly negative electron gain enthalpies. Why?
Answer:

• Group 16 (chalcogens) and Group 17 (halogens) are interested to add two or one electrons respectively to attain a stable noble gas configuration.
• Because of this interest, these elements have highly negative electron gain enthalpies.

Question 16.
What is the effective nuclear charge? How is it approximated?
Answer:
The net nuclear charge experienced by valence electrons in the outermost shell is called the effective nuclear charge. It is approximated by the below-mentioned equation Z_eff = Z – S.
where Z is the atomic number and S is the screening constant which can be calculated using Slater’s rules.

Question 17.
Elements Zn, Cd, and Hg with electronic configuration (n-1)d¹⁰ ns² do not show most of the transition elements properties. Give reason.
Answer:

• Zn, Cd, and Hg are having completely filled d-orbitais (d¹⁰ electronic configuration).
• They do not have partially filled d-orbitais Like other transition elements. So they do not show much of the transition elements properties.

Question 18.
Define Ionisation energy.
Answer:
Ionization energy is defined as the minimum amount of energy required to remove the most loosely bound electron from the valence shell of the isolated neutral gaseous atom in its ground state.

Question 19.
Why d-block elements are called transition elements?
Answer:
d-block elements form a bridge between the chemically active metals of s-block elements and the less active elements of groups of 13^th and 14^th and thus take their familiar name transition elements.

Question 20.
Beryllium has higher ionization energy than Boron. Give reason.
Answer:
Beryllium has completely filled 2s orbital which is more stable than the partially filled valence shell electronic configuration of Boron (2s² – 2p¹). Hence, Beryllium has higher ionization energy than Boron.

Question 21.
Write the electronic configuration of lanthanides and actinides?
Answer:

• The electronic configuration of lanthanides is 4f^1-144 5d^0-11 6s².
• The electronic configuration of actinides is 5f^1-14 6d^0-17s².

Question 22.
What is the effect of shielding on ionization energy?
Answer:
As we move down a group, the number of inner-shell electrons increases which in turn increases the repulsive force exerted by them on the valence electrons, i.e., the increased shielding effect caused by the inner electrons decreases the attractive force acting the valence electron by the nucleus. Therefore, the ionization energy decreases.

Question 23.
Define electron affinity.
Answer:
Electron affinity is defined as the amount of energy released when an electron is added to the valence shell of an isolated neutral gaseous atom in its ground state to form its anion.

Question 24.
What are periodic properties? Give example.
Answer:
The term periodicity of properties indicates that the elements with similar properties reappear at certain regular intervals of atomic number in the periodic table.
Example:

• Atomic radii
• Ionization energy
• Electron affinity
• Electronegativity.

Question 25.
Why is the electron affinity of Nitrogen almost zero?
Answer:
Nitrogen has half-filled stable (1s², 2s², 2p³) electronic configuration. The addition of extra electrons will disturb their stable electronic configuration and it has almost zero electron affinity.

Question 26.
The cationic radius is smaller than its corresponding neutral atom. Justify this statement.
Answer:

• When a neutral atom loses one or more electrons it forms cation.
  Na → Na⁺ + e^–
• The radius of this cation (r_Na⁺)is decreased than its parent atom (r_Na).
• When an atom is charged to cation, the number of nuclear charges becomes greater than the number of orbital electrons. Hence the remaining electrons are more strongly attracted by the nucleus. Hence the cationic radius is smaller than its corresponding neutral atom.

Question 27.
Define electronegativity.
Answer:
Electronegativity is defined as the relative tendency of an element present in a covalently bonded molecule, to attract the shared pair of electrons towards itself.

Question 28.
What are isoelectronic ions? Give example.
Answer:
There are some ions of different elements having the same number of electrons are called isoelectronic ions.
Example: Na⁺ Mg²⁺, Al³⁺, F^–, O^2-, N^3-

Question 29.
What is the variation of electronegativity in a group?
Answer:
The electronegativity generally decreases down a group. As we move down a group, the atomic radius increases and the nuclear attractive force on the valence electron decreases. Hence, the electronegativity decreases.

Question 30.
The ionization energy of beryllium is greater than the ionization energy of boron. Why?
Answer:
Be (Z= 4) 1s² 2s². it has completely filled valence electrons, which requires high IE₁.
B (Z =5) 1s² 2s² 2p¹. It has incompletely filled valence electrons, which requires comparatively
less IE₁ Hence I.E₁ Be > I.E₁ B.

Question 31.
What is the diagonal relationship?
Answer:
On moving diagonally across the periodic table, the second and third-period elements show certain similarities. The similarity in properties existing between the diagonally placed elements is called the ‘diagonal relationship’.

Question 32.
Define electron gain enthalpy or electron affinity. Give its unit.
Answer:
The electron gain enthalpy of an element is the amount of energy released when an electron is added to the neutral gaseous atom.
A + electron → A^– + energy (E.A)
Unit of electron affinity is KJ mole^–.

II. Short Question and Answers (3 Marks):

Question 1.
How Moseley determined the atomic number of an element using X-rays?
Answer:

• Henry Moseley studied the X-ray spectra of several elements and determined their atomic numbers (Z).
• He discovered a correlation between atomic number and the frequency of X-rays generated by bombarding a clement with the high energy of electrons.
• Moseley correlated the frequency of the X-ray emitted by an equation as,
  \(\sqrt{v}\) = a (Z – b)
  Where υ = Frequency of the X-rays emitted by the elements.
  a and b = Constants.
• From the square root of the measured frequency of the X-rays emitted, he determined the atomic number of the element.

Question 2.
Write notes on Newlands classification of elements.
Answer:
Newland made an attempt to classify the elements and proposed the law of octaves. On arranging the elements in the increasing order of atomic weights, he observed that the properties of every eighth element are similar to the properties of the first element. This law holds good for lighter elements up to calcium.

Question 3.
Describe Mendeleev’s periodic classification of elements.
Answer:
Dmitriev Mendeleev proposed that “the properties of the elements are the periodic functions of their atomic weights” and this is called periodic law. Mendeleev listed the 70 known elements at that time in several vertical columns in order of increasing atomic weights. Thus, Mendeleev constructed the first periodic table based on the periodic law.

In the periodic table, he left some blank spaces since there were no known elements with the appropriate properties at that time. He and others predicted the physical and chemical properties of the missing elements. Eventually, these missing elements were discovered and found to have the predicted properties. For example, Gallium of group-III and Germanium of group- IV were unknown at that time. But Mendeleev predicted their existence and properties. After the discovery of the actual elements, their properties were found to match closely to their predicted by Mendeleev.

Question 4.
Write notes on Moseley’s work.
Answer:
Henry Mosley studied the characteristic X-rays spectra of several elements by bombarding them with high energy electrons and observed a linear correlation between atomic number and the frequency of X-rays emitted which is given by the following expression, √υ = a(Z – b)
where, υ is the frequency of the X-rays emitted by the element with atomic number ‘Z’; ‘a’ and ‘b’ are constants and have same values for all the elements. The plot of √υ against Z gives a straight line. Using this relationship, we can determine the atomic number of an unknown element from the frequency of X-rays emitted.

Question 5.
What are the reasons behind Moseley’s attempt in finding an atomic number?
Answer:

• The number of electrons increases by the same number as the increase in the atomic number.
• As the number of electrons increases, the electronic structure of the atom changes.
• Electrons in the out can not shell of an atom (valence shell electrons) determine the chemical properties of the elements.

Question 6.
What are s-block elements? Give their properties.
Answer:
The elements of group-1 and group-2 are called s-block elements, since the last valence electron enters the ns orbital.

• The group-1 elements are called alkali metals while group-2 elements are called alkaline earth metals.
• These are soft metals and possess low melting and boiling points with low ionization enthalpies.
• They are highly reactive and form ionic compounds.
• They are highly electropositive in nature and most of the elements imparts colour to the flame.

Question 7.
Explain the classification of elements based on electronic configuration.
Answer:

• The distribution of electrons into orbitais, s, p, d, and f of an atom is called its electronic configuration. The electronic configuration of an atom is characterized by a set of four quantum numbers, n, l, m, and s. of these the principal quantum number (n) defines the main energy level known as shells.
• The position of an element in the periodic table is related to the configuration of that element and thus reflects the quantum numbers of the last orbital filled.
• The electronic configuration of elements in the periodic table can be studied along with the periods and groups separately for the best classification of elements.
• Elements placed in a horizontal row of a periodic table is called a period. There are seven periods.
• A vertical column of the periodic table is called a group. A group consists of a series of elements having a similar configuration to the outermost shell. There are 18 groups in the periodic table.

Question 8.
What are d-block elements? Give their properties.
Answer:
The elements of the groups 3 to 12 are called d-block elements or transition elements with general valence shell electronic configuration ns^{1 – 2}, (n – 1 )d^{1 – 10}.

• These elements show more than one oxidation state and form ionic, covalent, and coordination compounds.
• They can form interstitial compounds and alloys which can also act as catalysts.
• These elements have high melting points and are good conductors of heat and electricity.

Question 9.
What is a covalent radius? Explain.
Answer:
Covalent radius is one-half of the internuclear distance between two identical atoms linked together by a single covalent bond. The internuclear distance can be determined using X-ray diffraction studies.
For example, the experimental intemuclear distance in Cl₂ molecule is 1.98 Å. The covalent radius of chlorine is calculated as follows,
d_{cl – cl} = r_cl + r_cl
r_cl = \(\frac{d_{c l-d t}}{2}=\frac{1.98}{2}\) = 0.99 Å .

The formation of a covalent bond involves the overlapping of atomic orbitals and it reduces the expected internuclear distance. Therefore, the covalent radius is always shorter than the actual atomic radius.

Question 10.
How is the covalent radius of an individual atom can be calculated?
Answer:
The covalent radius of an individual atom can be calculated using the internuclear distance (dA-B) between two different atoms A and B. The simplest method proposed by Schomaker and Stevenson is as follows.
d_{A – B} = r_A + r_B – 0.09(χ_A – χ_B)
where χ_A and χ_B are the electronegativities of A and B respectively in Pauling units. Here, χ_A > χ_B and radius is in Å.

Question 11.
Write about the electronic configuration of the 1^st and 2^nd periods.
Answer:
Electronic configuration of t period:
In 1 period only two elements are present. This period starts with the filling of electrons in the first energy level, n¹. This level has only one orbital as is. Therefore it can accommodate two electrons maximum.

Electronic configuration of 2nd period:
In the 2’ period 8 elements are present. This period starts with the filling of electrons in the second energy level, n = 2. In this level four orbitais (one 2s and three 2p) are present. Hence the second energy level can accommodate 8 electrons. Thus, the second period has eight elements.

Question 12.
Discuss the variation of electron affinity in the period.
Answer:
As we move from alkali metals to halogens in a period, generally electron affinity increases, i.e., the amount of energy released will be more. This is due to an increase in the nuclear charge and a decrease in the size of the atoms. However, in the case of elements such as beryllium and nitrogen the addition of extra electrons will disturb their stable electronic configuration and they have almost zero electron affinity.

Noble gases have stable ns², np⁶ configurations, and the addition of further electrons is unfavourable and requires energy. Halogens having the general electronic configuration of ns², np⁵ readily accept an electron to get the stable noble gas electronic configuration (ns², np⁶), and therefore, in each period the halogen has high electron affinity.

Question 13.
What are the two exceptions of block division in the periodic table?
Answer:
1. Helium has two electrons. Its electronic configuration is 1s². As per the configuration, it is supposed to be placed in ‘s’ block but actually placed in s group which belongs to ‘p’ block. Because it has a completely filled valence shell as the other elements present in the 18^th group. It also resembles 18^th group elements in other properties. Hence helium is placed with other noble gases.

2. The other exception is hydrogen. it has only one s-electron and hence can be placed in group 1. It can also gain an electron to achieve a noble gas arrangement and hence it can behave as halogens (17th group elements). Because of these assumptions, the position of hydrogen becomes a special case. Finally, it is placed separately at the top of the periodic table.

III. Long Question and Answers (5 Marks):

Question 1.
Describe Mosley’s work and Modern Periodic Law.
Answer:
Henry Mosley studied the characteristic X-rays spectra of several elements by bombarding them with high energy electrons and observed a linear correlation between atomic number and the frequency of X-rays emitted which is given by the following expression,
√υ = a(Z – b)
where, υ is the frequency of the X-rays emitted by the element with atomic number ‘Z’; ‘a’ and ‘b’ are constants and have the same values for all the elements. The plot of √υ against Z gives a straight line. Using this relationship, we can determine the atomic number of an unknown element from the frequency of X-rays emitted.

Based on his work, the modern periodic law was developed which states that, “the physical and chemical properties of the elements are periodic functions of their atomic numbers”. Based on this law, the elements were arranged in order of their increasing atomic numbers. This mode of arrangement reveals an important truth that the elements with similar properties recur after regular intervals. The repetition of physical and chemical properties at regular intervals is called periodicity.

Question 2.
The first ionization enthalpy of magnesium is higher than that of sodium. On the other hand, the second ionization enthalpy of sodium is very much higher than that of magnesium. Explain.
Answer:
The 1^st ionization enthalpy of magnesium is higher than that of Na⁺ due to higher nuclear charge and slightly smaller atomic radius of Mg than Na. After the loss of the first electron, N& formed has the electronic configuration of neon (2, 8). The higher stability of the completely filled noble gas configuration leads to very high second ionization enthalpy for sodium. On the other hand. Mg⁺ formed after losing first electron still has one more electron in its outermost (3s) orbital. As a result, the second ionization enthalpy of magnesium is much smaller than that of sodium.

Question 3.
By using Pauling’s method calculate the ionic radii of Na⁺ and F^– ions in the potassium chloride crystal. Given that dNa⁺ – F^– = 231 pm.
Answer:

Question 4.
Discuss the variation of electronic configuration along the periods.
Answer:
Each period starts with the element having general outer electronic configuration, ns¹ and ends with ns², np⁶ where n is the period number. The first period starts with the filling of valence electrons in is orbital, which can accommodate only two electrons. Hence, the first period has two elements, namely hydrogen and helium.

The second period starts with the filling of valence electrons in 2s orbital followed by three 2p orbitals with eight elements from lithium to neon. The third period starts with filling of valence electrons in the 3s orbital followed by 3p orbitals. The fourth period starts with filling of valence electrons from 4s orbital followed by 3d and 4p orbitals in accordance with Aufbau principle. Similarly, we can explain the electronic configuration of elements in the subsequent periods.

In the fourth period, the filling of 3d orbitals starts with scandium and ends with zinc. These 10 elements are called first transition series. Similarly, 4d, 5d and 6d orbitals are filled in successive periods and the corresponding series of elements are called second third and fourth transition series respectively.

In the sixth period the filling of valence electrons starts with 6s orbital followed by 4f, 5d and 6p orbitals. The filling up of 4f orbitals begins with Cerium (Z = 58) and ends at Lutetium (Z = 71). These 14 elements constitute the first inner-transition series called Lanthanides. Similarly, in the seventh period 5f orbitals are filled, and it’s -14 elements constitute the second inner-transition series called Actinides. These two series are placed separately at the bottom of the modem periodic table.

Question 5.
Describe the nomenclature of elements with Atomic Number greater than 100.
Answer:
Usually, when a new element is discovered, the discoverer suggests a name following IUPAC guidelines which will be approved after a public opinion. In the meantime, the new element will be called by a temporary name coined using the following IUPAC rules until the IUPAC recognizes the new name.
1. The name was derived directly from the atomic number of the new element using the following numerical
roots.

2. The numerical roots corresponding to the atomic number are put together and ‘ium’ is added as suffix.
3. The final ‘n’ of ‘enn is omitted when it is written before ‘nil’ similarly the final ‘i’ of ‘bi’ and ‘tri’ is omitted when it written before ‘ium’.
4. The symbol of the new element is derived from the first letter of the numerical roots.

Question 6.
Explain the merits of Moseley’s long form of the periodic table.
Answer:
Merits of Moseley’s long form of the periodic table:

•  As this classification is based on atomic number, it relates the position of an element to its electronic configuration.
• The elements having similar electronic configuration fall in a group. They also have similar physical and chemical properties.
• The completion of each periõd is more logical. In a period as the atomic number increases, the energy shells are gradually filled up until an inert gas configuration is reached.
• The position of zero group is also justified in the table as group 18.
• The table completely separates metals and non-metals.
• The table separates two subgroups. lanthanides and actinides, dissimilar elements do not fall together.
• The greatest advantage of this periodic table is that this can be divided into four blocks namely s, p. d, and f-block elements.
• This arrangement of elements is easier to remember, understand and reproduce.

Question 7.
Explain the variation of the atomic radius in periods and groups.
Answer:
Variation in a period:
Atomic radius tends to decrease in a period. As we move from left to right along a period, the valence electrons are added to the same shell. The simultaneous addition of protons to the nucleus increases the nuclear charge, as well as the electrostatic attractive force between the valence electrons and the nucleus. Therefore atomic radius decreases along a period.

Variation in a group:
In the periodic table, the atomic radius of elements increases down the group. As we move down a group, new shells are opened to accommodate the newly added valence electrons. As a result, the distance between the centre of the nucleus and the outermost shell containing the valence electron increases. Hence, the atomic radius increases.

Question 8.
What is an Effective nuclear charge? How is it calculated using slater’s rule?
Answer:
In addition to the electrostatic forces of attraction j between the nucleus and the electrons, there | exists repulsive forces among the electrons. The repulsive force between the inner shell electrons j and the valence electrons leads to a decrease in the j electrostatic attractive forces acting on the valence 1 electrons by the nucleus. Thus, the inner shell | electrons act as a shield between the nucleus and the valence electrons. This effect is called the shielding effect.

The net nuclear charge experienced by valence electrons in the outermost shell is called the effective 1 nuclear charge. It is approximated by the below-mentioned equation.
Z_eff = Z – S
Where Z is the atomic number and ‘S’ is the screening constant which can be calculated using Slater’s rules as described below.
Step 1:
Write the electronic configuration of the atom and rearrange it by grouping ns and np orbitals together and others separately in the following form.
(1s)(2s, 2p) (3s, 3p) (3d) (4s, 4p) (4d) (4f) (5s, 5p) ……

Step 2:
Identify the group in which the electron of interest is present. The electron present right to this ! group does not contribute to the shielding effect. Each of the electrons within the identified group (denoted by ‘n’) shields to, an extent of 0.35 unit of nuclear charge. However, it is 0.30 unit for 1s electron.

Step 3:
Shielding of inner-shell electrons. If the electron of interest belongs to either s or p orbital,
(i) each electron within the (n – 1) group shields to an extent of 0.85 unit of nuclear charge, and
(ii) each electron within the (n – 2) group (or) even lesser group (n – 3), (n – 4) etc…
completely shields i.e. to an extent of 1.00 unit of nuclear charge.

If the electron of interest belongs to d or f orbital, then each of electron left of the group of electron of interest shields to an extent of 1.00 unit of nuclear charge.

Step 4:
Summation of the shielding effect of all the electrons gives the shielding constant ‘S’.

Question 9.
Explain the periodic variation of ionization energy in a period.
Answer:
The ionization energy usually increases along a period with few exceptions. When we move from left to right along a period, the valence electrons are added to the same shell, at the same time protons are added to the nucleus, This successive increase of nuclear charge increases the electrostatic attractive force on the valence electron and more energy is required to remove the valence electron resulting in high ionization energy. Consider the variation in ionization energy of second period elements. The plot of atomic number vs ionisation energy is given below.

In the graph, there are two deviations in the trends of ionisation energy. It is expected that boron has higher ionisation energy than beryllium since it has higher nuclear charge. However, the actual ionisation energies of beryllium and boron are 899 and 800kJ mol^-1 respectively contrary to the expectation. It is due to the fact that beryllium with completely filled 2s orbital, is more stable than partially filled valence shell electronic configuration of boron. (2s², 2p¹).

The electronic configuration of beryllium (Z = 4) in its ground state is 1s², 2s² and that of boron (Z = 5) 1s², 2s², 2p¹. Similarly, nitrogen with 1s², 2s², 2p¹ electronic configuration has higher ionisation energy (l402 kJmol^-1) than oxygen (1314 kJmol^-1). Since the half-filled electronic configuration is more stable, it requires higher energy to remove an electron from 2p orbital of nitrogen. Whereas the removal of one 2p electron from oxygen leads to a stable half-filled configuration. This makes it comparatively easier to remove 2p electron from oxygen.

Question 10.
Explain the periodic variation of electron affinity in a group.
Answer:
Electron affinity is defined as the amount of energy released (required in the case of noble gases) when an electron is added to the valence shell of an isolated ^neutral gaseous atom in its ground state to form its anion. It is expressed in kJmol^-1
A + 1e^– → A^– + E_A

Variation of Electron Affinity in a period:
As we move from alkali metals to halogens in a period, generally electron affinity increases, i.e., the amount of energy released will be more. This is due to an increase in the nuclear charge and a decrease in size of the atoms. However, in case of elements such as beryllium (1s², 2s²), nitrogen (1s², 2s², 2p³) the addition of extra electron will disturb their stable electronic configuration and they have almost zero electron affinity.

Noble gases have stable ns², np⁶ configurations, and the addition of further electrons is unfavourable and requires energy. Halogens having the general electronic configuration of ns², np⁵ readily accept an electron to get the stable noble gas electronic configuration (ns², np⁶), and therefore in each period the halogen has high electron affinity, (high negative values)

Question 11.
Define electron affinity. How does it vary along with the group?
Answer:
Electron affinity is defined as the amount of energy released (required in the case of noble gases) when an electron is added to the valence shell of an isolated neutral gaseous atom in its ground state to form its anion. It is expressed in kJmoF1
A + 1e^– → A^– + E_A

Variation of Electron affinity in a group:
As we move down a group, generally the electron affinity decreases. It is due to an increase in atomic size and the shielding effect of inner-shell electrons. However, oxygen and fluorine have lower affinity than sulphur and chlorine respectively. The sizes of oxygen and fluorine atoms are comparatively, small and they have high electron density.

Moreover, the extra electron, added to oxygen and fluorine has to be accommodated in the 2p orbital which is relatively compact compared to the 3p orbital of sulphur and chlorine so, oxygen and fluorine have lower electron affinity than their respective group elements sulphur and chlorine.

Question 12.
Explain the salient features of groups.
Answer:
1. Number of electrons in the outermost shell:
The number of electrons present in the outermost shells does not change on moving down in a group, i.e remains the same. Hence, the valency also remains the same within a group.

2. Number of shells:
In going down a group the number of shells increases by one at each step and ultimately becomes equal to the period number to which the element belongs.

3. Valency:
The valencies of all the elements of the same group are the same. The valency of an element with respect to oxygen is same in a group.

4. Metallic character:
The metallic character of the elements increases in moving from top to bottom in a group.

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Bio Botany Guide Pdf Chapter 7 Cell Cycle Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Bio Botany Solutions Chapter 7 Cell Cycle

11th Bio Botany Guide Cell Cycle Text Book Back Questions and Answers

Choose The Correct Answer:

Question 1.
The correct sequence in cell cycle is
a) S M G1 G2
b) S G1 G2 M
c) G1 S G2 M
d) M G1 G2 S
Answer:
c) G1 S G2 M

Question 2.
If mitotic division is restricted in G, phase the cell cycle, then the condition is known as
a) S Phase
b) G₂ Phase
c) M Phase
d) G₀ phase
Answer:
d) G₀ phase

Question 3.
Anaphase promoting complex APC is a protein degradation machinery necessary for proper mitosis of animal cells. If APC is defective in a human cells. Which of the following is expected to occur?
a) Chromosomes will be fragmented
b) Chromosomes will not condense
c) Chromosomes will not regregate
d) Recombination of Chromosomes will occur
Answer:
c) Chromosomes will not segregate

Question 4.
In the S phase of cell cycle
a) Amount of DNA doubles in each cell
b) Amount of DNA remain same in each cell
c) Chromosome number is increased
d) Amount of DNA is reduced to half in each cell
Answer:
a) Amount of DNA doubles in each cell

Question 5.
The centromere is required for
a) Transcription
b) Crossing over
c) Cytoplasmic cleavage
d) movement of chromosome towards the pole
Answer:
d) movement of chromosome towards the pole

Question 6.
Synapsis occurs between
a) m RNA and ribosomes
b) spindle fibres and centromeres
c) two homologous chromosomes
d) a male and a female gemale
Answer:
c) two homologous chromosomes

Question 7.
In meiosis crossing over is initiated at
a) Diplotene
b) Pachytene
c) Leptotene
d) Zygotene
Answer:
b) Pachytene

Question 8.
Colchicine prevents the mitosis of the cells at which of the following stage
a) Anaphase
b) Metaphase
c) Prophase
d) Interphase
Answer:
a) Anaphase

Question 9.
The pairing of homologous chromosomes on meiosis is known as
a) Bivalent
b) Synapsis
c) Disjunction
d) Synergids
Answer:
b) Synapsis

Question 10.
Anastral mitosis is the characteristic feature of
a) Lower animals
b) Higher animals
c) Higher plants
d) All living Organism
Answer:
c) Higher plants

Question 11.
Write any three significance of mitosis
Answer:
Exact copy of the parent cell is produced by mitosis (genetically identical).

1. Genetic stability – daughter cells are genetically identical to parent cells.
2. Repair of tissues – damaged cells must be replaced by identical new cells by mitosis.
3. Regeneration – Arms of starfish.

Question 12.
Differentiate between Mitosis and Meiosis.
Answer:
Differences between Mitosis and Meiosis

Question 13.
Differentiate Cytokinesis in plant cells & animal cells
Answer:

Question 14.
Given an account of the Go phase.
Answer:
Some cells exit G₁ and enters a quiescent stage called G₀, where the cells remain metabolically active without proliferation. Cells can exist for long periods in G₀ phase. In G₀ cells cease growth with reduced rate of RNA and protein synthesis. The G₀ phase is not permanent. Mature neuron and skeletal muscle cell remain permanently in G₀. Many cells in animals remains in G₀ unless called onto proliferate by appropriate growth factors or other extracellular signals. G₀ cells are not dormant.

Question 15.
Write about the Pachytene and Diplotene stage of Prophase I.
Answer:

3. Pachytene stage

• Chromosome appear as bivalent or tetrads
• 4 chromatids & 2 centromeres are seen
• Synapsis of homologous chromosomes between non-sister chromatids completes except at chiasmata where crossing over occurs
• Recombination (exchange of chromosomal bits is completed by the end) – but chromosomes are linked at the sites of crossing over
• Enzyme – Recombinase mediates the process.

4. Diplotene

• Synaptonemal complex disassembled & dissolves
• Nonsister chromatids of homologous chromosomes get attached where x like shape occur at Crossing over known as chiasmata holding the homologous chromosomes together the homologous chromosomes tend to separate except at chiasmat
• The sub-stage last for days or years depending on the sex & the organism follows Pachytene
• synaptical complex disassembled & dissolves
• The chromosomes are actively transcribed in females as the eggs stores up materials for embryonic development
• Exception In Lamp brush chromosome prominent loops occur.
  

11th Bio Botany Guide Cell Cycle Additional Important Questions and Answers

I.Choose the correct answer: (1 Marks)

Question 1.
Most of the neurons in the brain are in …………… stage.
(a) G₁
(b) S
(c) G₂
(d) G₀
Answer:
(d) G₀

Question 2.
Un differentiated cells include
a) Stem cells in animals
b) Meristematic cells in plants
c) RBC which carry out the transportation of oxygen
d) Mesophyll cells which carry out photosynthesis
(i) a & b
(ii) c & d
(iii) a & c
(iv) b & c
Answer:
(i) a & b

Question 3.
Robert Brown discovered the nucleus in the cells of …………… roots.
(a) Mirabilis
(b) Orchid
(c) Moringa
(d) Oryza
Answer:
(b) Orchid

Question 4.
The proteins that activate the cell to perform cell division are
a) Actin and Myosin
b) Kinases and Cyclin
c) Histamine and Cyclin
d) Tubulin and Actin
Answer:
b) Kinases & Cyclin

Question 5.
The number of chromosomes in the onion cell is …………….
(a) 8
(b) 16
(c) 32
(d) 64
Answer:
(a) 16

Question 6.
Mitosis is called
a) Direct cell division
b) Indirect cell division
c) Mitotic Meiotic cell division
d) Reduction division
Answer:
a) Direct cell division

Question 7.
During Anaphase
(I) The daughter chromosome move to the opposite poles due to the shortening of the phragmoplast
(II) due to the thickening of chromosomes
(III) Shortening of microtubules
(IV) Shortening of asters
Answer:
(III) Shortening of microtubules

Question 8.
Cell cycle was discovered by …………….
(a) Singer & Nicolson
(b) Prevost & Dumans
(c) Schleider & Schwann
(d) Boveri
Answer:
(b) Prevost & Dumans

Question 9.
The cells without nucleus are
a) RBC – platelets, tracheids & vessels
b) RBC – sievetube, companion cells thrombocytes
c) WBC – platelets, companion cells & vessels
d) RBC – platelets, companion cells & neurons
Answer:
a) RBC – platelets, tracheids & vessels

Question 10.
The stage between two meiotic division is called
a) Cytokinesis
b) Interphase I
c) Inter kinesis
d) Interphase II
Answer:
c) Inter kinesis

Question 11.
Replication of DNA occurs at …………… phase.
(a) G₀
(b) G₁
(c) S
(d) G₂
Answer:
(c) S

II. Find out the true and false statements from the following and on that basis find the correct answer.

Question 1.
(I) Nucleolus disappear during the metaphase stage of mitosis
(II) The microtubules arrange to form asters in plant cells
(III) In plant cells phragmoplast is formed prior to the formation of cell plate
(IV) Mitosis is responsible for the Regeneration of lost arms of starfish

Answer:
b) False – False – True- True

Question 2.
(i) The word Protoplasm was coined by – Purkinje
(ii) Structure of bacteria was observed first – Edouard Van Beneden through a microscope by
(iii) Centrosome & Chromosome theory – Theodor Boveri Proposed by
(iv) Cell division in round Worm was – Walther Flemming Observed by

Answer:
b) True – False – True – False

Question 3.
(i) C Value is the amount in picograms of DNA contained within a haploid Nucleus
(ii) Nucleolan membrane disappear during Ana Phase stage of mitosis
(iii) The arrangement of microtubules is called to form Asters -, which is a unique feature of plant cells
(iv) One of the protein synthesis in G2 – phase is known as Maturation Promoting Factor

Answer:
a) True – False – False – True

III. Find out the correct match from the following.

Question 1.
Zygotene – Chromosomes appear as tetrads
Pachytene – Synapsis of homologous chromosomes occur
Diplotene – Condensation of chromosomes takes place
Diakinesis – Terminalisation of chiasmata occur & Nucleolus Disappear
Answer:
Diakinesis -Terminalisation of chiasmata occur & Nucleolus Disappear

Question 2.
Duration of different Phases of cell cycle given find out the correct match
(I) S Phase – 12 Hours
(II) G1 Phase – 11 Hours
(III) G2 Phase – 4 Hours
(IV) M Phase – 2 Hours
Answer:
(III) G2 Phase – 4 Hours

IV. Find out the Wrong match

Question 1.
(I) The chromosome does not divide as chromatids, for centromere does not divide – Anaphase I
(II) The chromatids move to the opposite poles by the splitting of the centromere – Anaphase
(III) Sister chromatids get separated by splitting of Centromere – Anaphase II
(IV) Homologous chromosomes appear as bivalent or tetrad – Metaphase II
Answer:
(IV) Homologous chromosomes appear as bivalent or tetrad – Metaphase II

Question 2.
Most nëurons remain in G-’o’ stage do not divide
(I) This technique can be applied to replace neurons in dementia patients
(II) neurons can be activated by giving electric shocks
(III) neurons can be replaced by surgical procedures
(IV) Dead or injured neurons can be replaced by stem cell therapy
Answer:
(IV) Dead or injured neurons can be replaced by stem cell therapy

V.

Question 1.
Match the following and find the
(I) Robert Brown – A) Coined the word cell
(II) Robert Hook – B) Coined the word Mitosis
(III) Schleiden & Schwann – C) Studied the presence of Nucleus in cells
(IV) Waither Flemming – D) Cell theory

Answer:
d) C-A- D- B

Question 2.
(I) Cell cycle – A) division that follows the nuclear division
(II) Restriction point – B) Longest part but not resting stage
(III) lnterphae – C) A series of events leading to the formation of a new Cell
(IV) Cytokinesis – D) The checkpoint at the end of Gi determine a cell’s fate

Answer:
c) C-D- B- A

VI. 

Question 1.
Read the following Assertion and Reason. Find the correct answer
Assertion A: The mitochondrial inheritance in higher animals is uniparental
Reason R: The mitochondria from the male partner either undergo degeneration or rejected and only mitochondria from egg or ova is accepted.
(a) Assertion and Reason are correct Reason is explaining assertion
(b) Assertion and Reason are correct, but the reason is not explaining assertion
(c) Assertion is true but Reason not explaining assertion
(d) Assertion is true but Reason is wrong
Answer:
a) Assertion and Reason are correct. Reason is explaining assertion

Question 2.
Assertion A: In Meiosis Prophase I is a longer but significant phase
Reason R: Chiasma formation and crossing over takes place and recombination takes place
(a) Assertion and Reason are correct Reason is explaining Assertion
(b) Assertion and Reason are correct but Reason is not explaining Assertion
(c) Assertion is true but Reason is wrong
(d) Assertion is true but Reason not explaining Assertion
Answer:
b) Assertion and Reason are correct but Reason is not explaining Assertion

Question 3.
Assertion A: Interphase is the longest part of cell division and the cell actively involved protein synthesis & DNA synthesis
Reason: The Interphase is also known as the resting phase, & the cell takes rest between successive cell division
(a) Assertion and Reason are correct Reason is explaining Assertion
(b) Assertion and Reason are correct but Reason is not explaining Assertion
(c) Assertion is true but Reason is wrong
(d) Assertion is true but Reason not explaining assertion
Answer:
c) Assertion is true but Reason is wrong

Question 4.
Assertion A: The sister chromatids of homologous chromosomes exchange chromosomal bits
Reason R: This process of exchange of chromosomal bits is known as crossing over
(a) Assertion and Reason are correct Reason is explaining Assertion
(b) Assertion and Reason are correct but Reason is not explaining Assertion
(c) Assertion is true but Reason is wrong
(d) Assertion is true but Reason not explaining assertion
Answer:
d) Assertion is true but Reason not explaining assertion

VII. 

Question 1.
See the diagram & label the parts

Answer:
A – Leptotene
B – Chromosomes are visible under a light microscope
C – Paired sister chromatids begin to condense

Question 2.
See the diagram and write the correct answer.

Answer:
a) Cell growth – Interphase – Mitotic phase – Cyto kinesis

Question 3.
See the diagram & label Find out the correct labelling.

Answer:
b) Centromere – Chromatin – Secondary constriction – Kinetochore

Question 4.
Label the diagram properly.

Answer:
A – Non-sister Chromatids
B – Centromere
C – Chiasma
D – Bivalent or Tetrad

Question 5.

Answer:
A – Outer kinetochore
B – Fibrous corona
C – Inner Kinetochore
D – Microtubules

2 Mark Questions.

Question 1.
Name the two types of nuclear division.
Answer:
The two types of nuclear division:

1. Mitosis and
2. Meiosis.

Question 2.
What are the reasons for the arresting growth of cell during G1 Phase?
Answer:

• Deprivation of nutrition
• Lack of growth factors or density-dependent inhibition occur
• Some metabolic changes leads to Go – stage

Question 3.
Point out the reasons responsible for the arresting of the cell in the G₁ phase?
Answer:
Cells are arrested in G₁ due to:

• Nutrient deprivation
• Lack of growth factors or density dependant inhibition
• Undergo metabolic changes and enter into G₀ state.

Question 4.
Differentiate between karyokinesis and Cytokinesis of Amitosis.
Answer:

Question 5.
Define amitosis & write about its drawbacks.
Answer:
Amitosis is known as Direct cell division or Incipient cell division.
No spindle formation, no condensation of chromatin material occur.

It has one 2 steps

1. Karyokinesis
2. Cytokinesis

Drawbacks: Causes unequal distribution of chromosomes Can lead to abnormalities in

• metabolism
• reproduction

Question 6.
Distinguish between Closed and Open mitosis.
Answer:

Question 7.
Differentiate between Anastral and Amphiastral cell division
Answer:

Question 8.
What happens to plant cells at the end of Telophase in Mitosis?
Answer:
In plants, phragmoplast are formed between the daughter cells. A cell plate is formed between the two daughter cells, reconstruction of cell wall takes place. Finally, the cells are separated by the distribution of organelles, macromolecules into two newly formed daughter cells.

Question 9.
Differentiate meiosis in Plants & Animals.
Answer:

Question 10.
Define Mitogens.
Answer:

• The biochemical substances or factors which promote cell cycle acceleration & proliferation is called Mitogen.
• Eg. Gibberellin, Ethylene, Indole Acelic Acid, Kinetin.
• They are also known as Growth promotors.

Question 11.
Explain briefly about Endomitosis.
Answer:
The replication of chromosomes in the absence of nuclear division and cytoplasmic division resulting in numerous copies within each cell is called endomitosis. Chromonema do not separate to form chromosomes but remain closely associated with each other. Nuclear membrane does not rupture. So no spindle formation. It occurs notably in the salivary glands of Drosophila and other flies. Cells in these tissues contain giant chromosomes (polyteny), each consisting of over thousands of intimately associated, or synapsed, chromatids. Example: Polytene chromosome.

3 Mark Questions

Question 1.
Write down the significance of Meiosis.
Answer:

• Maintain chromosome number constant
• Crossing over (exchange of genetic meterial) leads to variations
• Variation – the raw material for Evolution
• Finally, meiosis produces genetic variability by partitioning different combinations of genes into gametes through an independent assortment.
• Responsible for Adaptations of organisms to various environmental stress.

Question 2.
Differentiate between Mitosis in Plants & Animals.
Answer:

Question 3.
Explain Endomitosis.
Answer:
Sometimes, the replication of chromosomes occur in the absence of karyokinesis & cytokinesis resulting in numerous copies within each cell condition known as Endomitosis.

• Chromonema donot separate to form Chromosomes
• Nuclear membrance does not repture
• No spindle formation occur
• Each chromosome consisting of over thousands of synapsed Chromatids
  Eg – Salvary gland chromosome of Drosophila (Polytene or Chromosome).

Question 4.
Differentiate between Anaphase I & Anaphase II of Meiosis.
Answer:

5 Mark Questions

Question 1.
Explain in detail the various stages of Prophase I.
Answer:
The various stages of Prophase I:
1. Prophase I – Prophase I is of longer duration and it is divided into 5 substages – Leptotene, Zygotene, Pachytene, Diplotene and Diakinesis.

2. Leptotene – Chromosomes are visible under light microscope. Condensation of chromosomes takes place. Paired sister chromatids begin to condense.

3. Zygotene – Pairing of homologous chromosomes takes place and it is known as synapsis. Chromosome synapsis is made by the formation of synaptonemal complex. The complex formed by the homologous chromosomes are called as bivalent (tetrads).

4. Pachytene – At this stage bivalent chromosomes are clearly visible as tetrads. Bivalent of meiosis I consists of 4 chromatids and 2 centromeres. Synapsis is completed and recombination nodules appear at a site where crossing over takes place between non – sister chromatids of homologous chromosome. Recombination of homologous chromosomes is completed by the end of the stage but the chromosomes are linked at the sites of crossing over. This is mediated by the enzyme recombinase.

5. Diplotene – Synaptonemal complex disassembled and dissolves. The homologous chromosomes remain attached at one or more points where crossing over has taken place. These points of attachment where ‘X’ shaped structures occur at the sites of crossing over is called.

6. Chiasmata: Chiasmata are chromatin structures at sites where recombination has been taken place. They are specialised chromosomal structures that hold the homologous chromosomes together. Sister chromatids remain closely associated whereas the homologous chromosomes tend to separate from each other but are held together by chiasmata. This substage may last for days or years depending on the sex and organism. The chromosomes are very actively transcribed in females as the egg stores up materials for use during embryonic development. In animals, the chromosomes have prominent loops called lampbrush chromosome.

7. Diakinesis – Terminalisation of chiasmata. Spindle fibres assemble. Nuclear envelope breaks down. Homologous chromosomes become short and condensed. Nucleolus disappears.

Question 2.
Explain karyokinesis in mitosis of plant cell
Answer:

Prophase – Longest Phase

• Chromosomes visible thread like condenses into thick chromosomes
• Initiation of spindle fibres occur
• Nucleolus disappear Nuclear envelope breaks down
• Golgi apparatus & ER not seen

Metaphase

• Sister chromatids attached to spindle fibres by kinetochore of centromere
• Chromosome align on the equatorial plane (metaphase plate)
  (spindle assembly check point decide the fate of the cell)

Anaphase

• Centromere split daughter chromatids move to opposite poles
• Shortening of spindle create pull divide centromere & divide chromosome into a chromatids
  (APC /C leads to degradation of protein lead to separation of chromatids

Telophase

• Genetic material division completed Nucleolus & Nuclear membrane reform.
• Sister chromatids become thick chromosomes with its own centromere.

Question 3.
Explain S phase & G2 phase, til S Phase
Answer:
(i) S Phase:

• Known as synthetic phase of interphase of mitosis
• Growth of cell continues
• Replication of DNA occur
• Histones synthesised and attach to DNA
• Duplication of centrioles occur
• DNA content doubles from 2C to 4C

(ii) G2 phase

• 4 C amount of DNA
• Cell growth continues
• Synthesis of
  • organelle,
  • mitochondria & chloroplast
  • tubulin synthesised, microtubules formed
• Spindle begin to occur
• Nuclear division follows
• MPF (Maturation Promoting factor) formed brings out condensation of interphase chromosomes into mitotic form.

Question 4.
Draw the Cell cycle.
Answer:

Question 5.
What are the significances of Mitosis.
Answer:
Exact copy of the parent cell is produced by mitosis (genetically identical).

1. Genetic stability – Daughter cells are genetically identical to parent cells.
2. Growth – As multicellular organisms grow, the number of cells making up their tissue increases. The new cells must be identical to the existing ones.
3. Repair of tissues – Damaged cells must be replaced by identical new cells by mitosis.
4. Asexual reproduction – Asexual reproduction results in offspring that are identical to the parent. Example Yeast and Amoeba.
5. In flowering plants, structure such as bulbs, corms, tubers, rhizomes and runners are produced by mitotic division. When they separate from the parent, they form a new individual. The production of large numbers of offsprings in a short period of time, is possible only by mitosis. In genetic engineering and biotechnology, tissues are grown by mitosis (i.e. in tissue culture).
6. Regeneration – Arms of starfish

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Physics Guide Pdf Chapter 11 Waves Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Physics Solutions Chapter 11 Waves

11th Physics Guide Waves Book Back Questions and Answers

I. Multiple choice questions:

Question 1.
A student tunes his guitar by striking a 120 Hertz with a tuning fork, and simultaneously plays the 4^th string on his guitar. By keen observation, he hears the amplitude of the combined sound oscillating thrice per second. Which of the following frequencies is the most likely the frequency of the 4th string on his guitar?
(a) 130
(b) 117
(c) 110
(d) 120
Answer:
(b) 117

Hint:
Frequency of the fourth string can be derived from harmonic series generated by the strings.
Frequencies of first 4 strings are 120, 119, 118, 117 Hz.
f₄ = 117Hz

Question 2.
A transverse wave moves from a medium A to a medium B. In medium A, the velocity of the transverse wave is 500 ms^-1 and the wavelength is 5 m. The frequency and the wavelength of the wave in medium B when its velocity is 600 ms^-1, respectively are:
(a) 120 Hz and 5 m
(b) 100 Hz and 5 m
(c) 120 Hz and 6 m
(d) 100 Hz and 6 m
Answer:
(d) 100 Hz and 6 m

Hint:
v_A = 500 ms^-1; λ_A = 5 m
∴ Frequency in medium B
f_B = \(\frac{v_{\mathrm{A}}}{\lambda_{\mathrm{A}}}\) = \(\frac { 500 }{ 5 }\) = 100 Hz
Wavelength in medium B is
λ_B = \(\frac{v_{\mathrm{B}}}{f_{\mathrm{B}}}\) = \(\frac { 600 }{ 100 }\) = 6m

Question 3.
For a particular tube, among six harmonic frequencies below 1000 Hz, only four harmonic frequencies are given: 300 Hz, 600 Hz, 750 Hz and 900 Hz. What are the two other frequencies missing from this list?
(a) 100 Hz, 150 Hz
(b) 150 Hz, 450 Hz
(c) 450 Hz, 700 Hz
(d) 700 Hz, 800 Hz
Answer:
(b) 150 Hz, 450 Hz

Hint: Fundamental frequency f₀ = 150 Hz
From the series of frequencies we get
f₁ = 2f₀
f₂ = 3f₀
= 3 x 150
= 450 Hz

Question 4.
Which of the following options is correct?

Options for (1), (2) and (3), respectively are:
(a) (b), (c) and (a)
(b) (c), (a) and (b)
(c) (a), (b) and (c)
(d) (b), (a) and (c)
Answer:
(a) (b), (c) and (a)

Question 5.
Compare the velocities of the wave forms given below, and choose the correct option.

where, v_A, v_B, v_C and v_D are velocities given in (a), (b), (c) and (d), respectively.
(a) v_A > v_B > v_D > v_C
(b) v_A < v_B < v_D < v_C
(c) v_A = v_B = v_D = v_C
(d) v_A > v_B = v_D > v_C
Answer:
(c) v_A = v_B = v_D = v_C

Hint:
The amplitude of the velocity waves is same in all four cases.

Question 6.
A sound wave whose frequency is 5000 Hz travels in air and then hits the water surface. The ratio of its wavelengths in water and air is:
(a) 4.30
(b) 0.23
(c) 5.30
(d) 1.23
Answer:
(a) 4.30

Hint:
Frequency = 5000 Hz
Speed of sound in air v_air = 332 m/s
Speed of sound in water v_water = 1450 m/s

Question 7.
A person standing between two parallel hills fires a gun and hears the first echo after t₁ sec and the second echo after t₂ sec. The distance between the two hills is:
(a) \(\frac{v\left(t_{1}-t_{2}\right)}{2}\)
(b) \(\frac{v\left(t_{1} t_{2}\right)}{2\left(t_{1}+t_{2}\right)}\)
(c) v(t₁ + t₂)
(d) \(\frac{v\left(t_{1}+t_{2}\right)}{2}\)
Answer:
(d) \(\frac{v\left(t_{1}+t_{2}\right)}{2}\)

Hint:
For first echo 2d₁ = vt₁
For second echo 2d₂ = vt₂
∴ d = d₁ + d₂ = \(\frac{v\left(t_{1}+t_{2}\right)}{2}\)

Question 8.
An air column in a pipe which is closed at one end, will be in resonance with the vibrating body of frequency 83 Hz. Then the length of the air column is:
(a) 1.5 m
(b) 0.5 m
(c) 1.0 m
(d) 2.0 m
Answer:
(c) 1.0 m

Hint:
l = \(\frac { λ }{ 4 }\); f = 83 Hz
v = 332 m/s
λ = \(\frac { v }{ f }\)
= \(\frac { 332 }{ 83 }\)
= 4 m
l = \(\frac { λ }{ 4 }\) = \(\frac { 4m }{ 4 }\) = 1m = 1.0 m

Question 9.
The displacement y of a wave travelling in the x direction is given by y = (2 x 10^-3) sin (300t – 2x + \(\frac { π }{ 4 }\)), where x and y are measured in metres and t in second. The speed of the wave is:
(a) 150 ms^-1
(b) 300 ms^-1
(c) 450 ms^-1
(d) 600 ms^-1
Answer:
(a) 150 ms^-1

Hint:
The given equation is similar to

Question 10.
Consider two uniform wires vibrating simultaneously in their fundamental notes. The tensions, densities, lengths and diameter of the two wires ,are in the ratio 8:1, 1:2, (x : y) and 4 : 1 respectively. If the note of the higher pitch has a frequency of 360 Hz and the number of beats produced per second is 10, then the value of (x : y) is:
(a) 36 : 35
(b) 35 : 36
(c) 1 : 1
(d) 1 : 2
Answer:
(a) 36 : 35

Hint:
No. of beats = 10
Frequency of higher pitch f₁ = 360 Hz
Frequency of lower pitch f₂ = 360 – 10 = 350 Hz
x : y = Ratio of length
l ∝ f
l₁ : l₂ = x : y = f₁ : f₂
= 360 : 350
= 36 : 35

Question 11.
Which of the following represents a wave:
(a) (x – vt)³
(b) x(x + vt)
(c) \(\frac { 1 }{ (x +vt) }\)
(d) sin(x + vt)
Answer:
(d) sin(x + vt)

Hint:
Wave must have a wave function.
Since y = a sin ωt

Question 12.
A man sitting on a swing which is moving to an angle of 60° from the vertical is blowing . a whistle which has a frequency of 2.0 k Hz. The whistle is 2.0 m from the fixed support point of the swing. A sound detector which detects the whistle sound is kept in front of the swing. The maximum frequency the sound detector detected is:
(a) 2.027 kHz
(b) 1.914 kHz
(c) 9.14 kHz
(d) 1.011 kHz
Answer:
(a) 2.027 kHz

Hint:

Question 13.
Let y = \(\frac{1}{1+x^{2}}\) at t = 0 be the amplitude of the wave propagating in the positive x-direction. At t = 2s, the amplitude of the wave propagating becomes y = \(\frac{1}{1+(x-2)^{2}}\). Assume that the shape of the wave does not
change during propagation. The velocity of the wave is:
(a) 0.5 ms^-1
(b) 1.0 ms^-1
(c) 1.5 ms^-1
(d) 2.0 ms^-1
Answer:
(b) 1.0 ms^-1

Hint:

Question 14.
A uniform rope having mass m hangs vertically from a rigid support. A transverse wave pulse is produced at the lower end. Which of the following plots shows the correct variation of speed v with height h from the lower end?

Answer:

Hint:
Speed varies exponentially with height h.

Question 15.
An organ pipe A closed at one end is allowed to vibrate in its first harmonic and another pipe B open at both ends is allowed to vibrate in its third harmonic. Both A and B are in resonance with a given tuning fork. The ratio of the length of A and B is:
(a) \(\frac { 8 }{ 3 }\)
(b) \(\frac { 3 }{ 8 }\)
(c) \(\frac { 1 }{ 6 }\)
(d) \(\frac { 1 }{ 2 }\)
Answer:
(d) \(\frac { 1 }{ 2 }\)

Hint:
First harmonic of a closed organ pipe
L_C = \(\frac { 3 λ }{ 4 }\)
Third harmonic of an open organ pipe
L₀ = \(\frac { 3 λ }{ 2 }\)
\(\frac{\mathrm{L}_{\mathrm{C}}}{\mathrm{L}_{\mathrm{O}}}\) = \(\frac { 3 π }{ 4 }\) x \(\frac { 3 }{ 3λ }\)
= \(\frac { 2 }{ 4 }\)
= \(\frac { 1 }{ 2 }\)
∴ \(\frac{\mathrm{L}_{\mathrm{C}}}{\mathrm{L}_{\mathrm{O}}}\) = \(\frac { 1 }{ 2 }\)

II. Short Answer Questions:

Question 1.
What is meant by waves?
Answer:
The disturbance which carries energy and momentum from one point in space to another point in space without the transfer of the medium is known as a wave.

Question 2.
Write down the types of waves.
Answer:
Waves can be classified into two types –

• Transverse waves
• Longitudinal waves

Question 3.
What are transverse waves? Give one example.
Answer:
In transverse wave motion, the constituents of the medium oscillate or vibrate about their mean positions in a direction perpendicular to the direction of propagation (direction of energy transfer) of waves.
Example: light (electromagnetic waves)

Question 4.
What are longitudinal waves? Give one example.
Answer:
The direction of vibration of particles in a medium is parallel to the direction of propagation of the wave.
Example: Sound waves traveling in air.

Question 5.
Define wavelength.
Answer:
For transverse waves, the distance between two neighbouring crests or troughs is known as the wavelength. For longitudinal waves, the distance between two neighbouring compressions or rarefactions is known as the wavelength. The SI unit of wavelength is meter.

Question 6.
Write down the relation between frequency, wavelength and velocity of a wave.
Answer:
Velocity of the wave is v = λf.

Question 7.
What is meant by the interference of waves?
Answer:
Interference is a phenomenon in which two waves moving in the same direction superimpose to form a resultant wave of greater, lower or the same amplitude.

Question 8.
Explain the beat phenomenon.
Answer:
When two or more waves superimpose each other with slightly different frequencies, then a sound of periodically varying amplitude at a point is observed. This phenomenon is known as beats. The number of amplitude maxima per second is called beat frequency. If we have two. sources, then their difference in frequency gives the beat frequency. Number of beats per second n = |f₁ – f₂| per second

Question 9.
Define intensity of sound and loudness of sound.
Answer:
“Loudness is defined as the degree of the sensation of sound produced in the ear or the perception of sound by the listener”. The intensity of sound is defined as “the sound power transmitted per unit area placed normal to the propagation of sound wave”.

Question 10.
Explain Doppler Effect.
Answer:
When the source and the observer are in relative motion with respect to each other and to the medium in which sound propagates, the frequency of the sound wave observed is different from the frequency of the source. This phenomenon is called Doppler Effect.

Question 11.
Explain red. shift and blue shift in Doppler Effect.
Answer:
If the spectral lines of the star are found to shift towards red end of the spectrum (called redshift) then the star is receding away from the Earth. If the spectral lines of the star are found to shift towards the blue end of the spectrum (called blue shift) then the star is approaching Earth.

Question 12.
What is meant by end correction in resonance air column apparatus?
Answer:
Since the antinodes are not exactly formed at the open end, we have to include a correction, called end correction e. It is calculated, by assuming that antinode is formed at a small distance above the open end e = 0.3 d.

Question 13.
Sketch the function y = x + a. Explain your sketch.
Answer:

Question 14.
Write down the factors affecting velocity of sound in gases.
Answer:
(i) Effect of pressure: Speed of sound is independent of pressure for a fixed temperature.

(ii) Effect of temperature: Speed of sound varies directly to the square root of temperature in kelvin. Speed of sound in air increases by 0.61 ms^-1 per degree celcius rise in temperature.

(iii) Effect of density: Velocity of sound in a gas is inversely proportional to the square root of the density of the gas.

(iv) Effect of moisture (humidity): Speed of sound increases with rise in humidity.

(v) Effect of wind: In the direction along the wind blowing, the speed of sound to wind blowing, the speed of sound decreases.

Question 15.
What is meant by an echo? Explain.
Answer:
An echo is a repetition of sound produced by the reflection of sound waves from a wall, mountain or other obstructing surfaces. The minimum distance from a sound-reflecting wall to hear an echo at 20°C is 17.2 meter.

III. Long Answer Questions:

Question 1.
Discuss how ripples are formed in still water.
Answer:
Suppose we drop a stone in a trough of still water, we can see a disturbance produced at the place where the stone strikes the water surface. We find that this disturbance spreads out (diverges out) in the form of concentric circles of ever-increasing radii (ripples) and strikes the boundary of the trough. This is because some of the kinetic energy of the stone is transmitted to the water molecules on the surface.

Actually, the particles of the water (medium) themselves do not move outward with the disturbance. This can be observed by keeping a paper strip on the water surface. The strip moves up and down when the disturbance (wave) passes on the water surface. This shows that the water molecules only undergo vibratory motion about their mean positions.

Question 2.
Briefly explain the difference between traveling waves and standing waves.
Answer:
Progressive waves:

1. Crests and troughs ate formed in transverse progressive waves. Compression and rarefaction are formed in longitudinal progressive waves. These waves move forward or backward in a medium i.e., they will advance in a medium with a definite velocity.
2. All the particles in the medium vibrate in such a way that the amplitude of the vibration for all particles is the same.
3. These waves carry energy while propagating.

Stationary waves:

1. Crests and troughs are formed in transverse stationary waves. Compression and rarefaction are formed in longitudinal stationary waves. These waves neither move forward nor backward in a medium i.e., they will not advance in a medium.
2. Except at nodes, all other particles of the medium vibrate such that the amplitude of vibration is different for different particles. The amplitude is minimum or zero at nodes and maximum at antinodes.
3. These waves do not transport energy.

Question 3.
Show that the velocity of a traveling wave produced in a string is v = \(\sqrt{\frac{T}{\mu}}\)
Answer:
Let us consider an elemental segment in the string as shown in the Figure. Let A and B be two points on the string at an instant of time. Let dl and dm be the length and mass of the elemental string, respectively. By definition, linear mass density, μ is

μ = \(\frac { dm }{ dl }\) … (1)
dm = μ dl … (2)
Consider an elemental string AB having a curvature which looks like an arc of a circle with centre at O, radius R and the arc subtending an angle θ at the origin O as shown in Figure. The angle 0 can be written in terms of arc length and radius as \(\frac { dl }{ R }\) = θ. The centripetal acceleration supplied by the tension in the string is
a_cp = \(\frac{v^{2}}{\mathrm{R}}\) … (3)
Then, centripetal force can be obtained when mass of the string (dm) is included in equation (3)
F_cp = \(\frac{(dm)v^{2}}{\mathrm{R}}\) … (4)
Experienced by elemental string can be calculated by substituting equation (2) in equation (4) we get the centripetal force as
\(\frac{(dm)v^{2}}{\mathrm{R}}\) = \(\frac{\mu v^{2} d l}{R}\) … (5)
The tension T acts along the tangent of the elemental segment of the string at A and B. Since the arc length is very small, variation in the tension force can be ignored. T can be resolved into horizontal component T cos (\(\frac { θ }{ 2 }\)) and vertical component T sin (\(\frac { θ }{ 2 }\)).

The horizontal components at A and B are equal in magnitude but opposite in direction. Hence, they cancel each other. Since the elemental arc length AB is taken to be very small, the vertical components at A and B appears to acts vertical towards the centre of the arc and hence, they add up. The net radial force F_r is
F_r = 2Tsin(\(\frac { θ }{ 2 }\)) … (6)
Since the amplitude of the wave is very small when it is compared with the length of the string, the sine of small angle is approximated
as sin (\(\frac { θ }{ 2 }\)) ≈ \(\frac { θ }{ 2 }\). Hence, equation (6) can be written as,
F_r = 2T x \(\frac { θ }{ 2 }\) = Tθ … (7)
But θ = \(\frac { dl }{ R }\), therefore substituting in equation (7), we get
F_r = T \(\frac { dl }{ R }\) … (8)
Applying Newton’s second law to the elemental string in the radial direction, under equilibrium, the radial component of the force is equal to the centripetal force. By equating equation (5) and equation (8), we get,
T \(\frac { dl }{ R }\) = μv²dl
v = \(\sqrt{\frac{\mathrm{T}}{\mu}}\) measured in ms^-1

Question 4.
Describe Newton’s formula for velocity of sound waves in air and also discuss the Laplace’s correction.
Answer:
Newton assumed that when sound propagates in air, the formation of compression and rarefaction takes place in a very slow manner so that the process is isothermal in nature. It is found that, the heat produced during compression (pressure increases, volume decreases), and heat lost during rarefaction (pressure decreases, volume increases) occur over a period of time such in a way that the temperature of the medium remains constant. Hence, by treating the air molecules to form an ideal gas, the changes in pressure and volume obey Boyle’s law, Mathematically
PV= Constant …(1)
Differentiating equation (1), we get
PdV + Vdp = 0
(or) P = – V\(\frac { dp }{ dv }\) = B_T … (2)
where, B_T is an isothermal bulk modulus of air.
v = \(\sqrt{\frac{\mathrm{B}}{\rho}}\) … (3)
Substituting equation (2) in equation (3), the speed of sound in air is
v_T = \(\sqrt{\frac{\bar{B}_{\mathrm{T}}}{\rho}}\) = \(\sqrt{\frac{\mathrm{P}}{\rho}}\)
Since P is the pressure of air whose value at NTP (Normal Temperature and Pressure) is 76 cm of mercury, we have
P = (0.76 x 13.6 x 10³ x 9.8)Nm^-2
ρ = 1.293 kg m^-3.
Here p is density of air. Then the speed of sound in air at normal temperature and pressure (NTP) is

But the speed of sound in air at 0°C is experimentally observed as 332 ms^-1 that is close up to 16% more than theoretical value.

Laplace correction: Laplace satisfactorily corrected this discrepancy by assuming that when the sound propagates through a medium, the particles oscillate very rapidly such that the compression and rarefaction occur very fast. Hence the exchange of heat produced due to compression and cooling effect due to rarefaction do not take place, because, air (medium) is a poor conductor of heat. Since, temperature is no longer considered as a constant here, propagation of sound is an adiabatic process. By adiabatic considerations, the gas obeys Poisson’s law (not Boyle’s law as Newton assumed), that is
PV’ = Constant … (4)
where, γ = \(\frac{\mathrm{C}_{\mathrm{p}}}{\mathrm{C}_{\mathrm{v}}}\), that is the ratio between specific heat at constant pressure and specific heat at constant volume.
Differentiating equation (4) on both the sides, we get
V^γ dP + P (γV^γ-1 dV) = 0
or, γP = – V\(\frac { dp }{ dv }\) = B_A … (5)
where, B_A is the adiabatic bulk modulus of air.
v = \(\sqrt{\frac{\mathrm{B}}{\rho}}\)
Now, substituting equation (5) in equation (6), the speed of sound in air is

Since air contains mainly, nitrogen, oxygen, hydrogen etc, (diatomic gas), we take γ = 1.47. Hence, speed of sound in air is v_A = (\(\sqrt{1.4}\))(280ms^-1) = 331.30 ms^-1, which is very much closer to experimental data.

Question 5.
Write short notes on reflection of sound waves from plane and curved surfaces.
Answer:
When the sound waves hit the plane wall, they bounce off in a manner similar to that of light. When a loudspeaker is kept at an angle with respect to a wall (plane surface), then the waves coming from the source (assumed to be a point source) can be treated as spherical wave fronts. Hence, the reflected wave front on the plane surface is also spherical, such that its centre of curvature can be treated as the image of the sound source (virtual or imaginary loud speaker) that can be assumed to be at a position behind the plane surface. These are shown in figures.

The behaviour of sound is different when it is reflected from different surfaces-convex or concave or plane. The sound reflected from a convex surface is spread out and so it is easily attenuated and weakened. Whereas, if it is reflected from the concave surface it will converge at a point and this can be easily amplified. The parabolic reflector (curved reflector) that is used to focus the sound precisely to a point is used in designing the parabolic mics which are known as high directional microphones.

We know that any surface (smooth or rough) can absorb sound. For instance, the sound produced in a big hall or auditorium or theatre is absorbed by the walls, ceilings, floor, seats etc. To avoid such losses, a curved sound board (concave board) is kept in front of the speaker, in such a way that the board reflects the sound waves of the speaker towards the audience. This method will minimize the spreading of sound waves in all possible direction in that hall it also enhances the uniform distribution of sound throughout the hall. Hence a person sitting at any position in that hall can hear the sound without any disturbance.

Question 6.
Briefly explain the concept of the superposition principle.
Answer:
When two or more waves in a medium overlap, their total displacement is the vector sum of the individual displacements.
Let us consider two functions which characterize the displacement of the waves, for example,
y₁ = A₁ sin(kx – ωt)
and y₂ = A₂ sin(kx – ωt)
Since both y₁ and y₂ satisfy the wave equation (solutions of wave equation) then their algebraic sum
y = y₁ + y₂
also satisfies the wave equation. It is meant that the displacements are additive.

Question 7.
Explain how the interference of waves is formed.
Answer:
Interference is a phenomenon in which two waves superimpose to form a resultant wave of greater, lower, or the same amplitude.

Let us consider two harmonic waves having identical frequencies, constant phase difference φ, and same waveform (can be treated as coherent source), but having amplitudes A₁ and A₂, then
y₁ = A₁ sin(kx – ωt) … (1)
y₂ = A₂ sin(kx – ωt) … (2)
Suppose they move simultaneously in a particular direction, then interference occurs (i.e., the overlap of these two waves). Mathematically y = y₁ + y₂ … (3)
Hence by substituting equation (1) and equation (2) in equation (3), we get

By squaring and adding equation (5) and (6), we get,
A² = A₁² + A₂² + 2A₁A₂cosφ … (8)
Since, intensity is square of the amplitude (I – A²), we get,
I = I₁ + I₂ + 2\(\sqrt{\mathrm{I}_{1} \mathrm{I}_{2}} \cos \varphi\) … (9)
This means the resultant intensity at any point depends on the phase difference at that point.

Question 8.
Describe the formation of beats.
Answer:
When two or more waves superimpose each other with slightly different frequencies, then a sound having periodically varying amplitude at a point is observed. This phenomenon is known as beats. The number of amplitude maxima per second is called beat frequency. If we have two sources, then their difference in frequency gives the beat frequency.
Number-of beats per second
n = \(\left|f_{1}-f_{2}\right|\) Per second

Question 9.
What are stationary waves? Explain the formation of stationary waves and also write down the characteristics of stationary waves.
Answer:
When the wave hits the rigid boundary it bounces back to the original medium and can interfere with the original waves. A pattern is formed, that is known as standing waves or waves stationary. Let us consider two harmonic progressive waves (formed by strings) that have the same amplitude and same velocity but move in opposite directions. Then the displacement of the first wave (incident wave) is
y₁ = A sin(kx – ωt) … (1)
(waves move toward right)
The displacement of the second wave (reflected wave) is
y₂ = A sin(kx + ωt) … (2)
(waves move toward left)
both will interfere with each other by the principle of superposition, the net displacement is
y = y₁ + y₂ … (3)
By substituting equation (1) and equation (2) in equation (3), we get
y = \(\left\{\begin{array}{l}
\mathrm{A} \sin (k x-\omega t) \\
+\mathrm{A} \sin (k x+\omega t)
\end{array}\right.\) … (4)
Using trigonometric identity, we rewrite equation (4) as
y(x, t) = 2A cos(ωt) sin(kx) … (5)
This represents a stationary wave or standing wave, It is meant that this wave does not move either forward or backward, whereas progressive or travelling waves will move forward or backward. In addition, the displacement of the particle in equation (5) can be written in more compact form,
y(x, t) = A’cos(cot)
where, A’ = 2A sin(Ax). It is implied implying that the particular element of the string executes simple harmonic motion with amplitude equals to A’. The maximum of this amplitude occurs at positions for which
sin(kx) = 1
⇒ kx = \(\frac { π }{ 2 }\), \(\frac { 3π }{ 2 }\), \(\frac { 5π }{ 2 }\), … = nπ
where m takes half-integer or half-integral values. The position of maximum amplitude is known as an antinode. Expressing wave number in terms of wavelength, let us represent the anti-nodal positions as
x_m = (\(\frac { 2m+1 }{ 2 }\)) \(\frac { λ }{ 2 }\) … (6)
where, m = 0, 1, 2 ….
For m = 0 we have maximum at
x₀ = \(\frac { λ }{ 2 }\)
For m = 1 we have maximum at
x₀ = \(\frac { 3λ }{ 4 }\)
For m = 2 we have maximum at
x₂ = \(\frac { 5λ }{ 4 }\)
and so on.
The distance between two successive antinodes can be computed by,

Similarly, the minimum of the amplitude A’ also occurs at some points in the space, and these points can be determined by setting
sin(kx) = 0
⇒ kx = 0, π, 2π, 3π, … = nπ
where n takes integer or integral values. It is noted that the elements at these points do not vibrate (not move), and the points are called nodes. The n^th nodal positions is given by,
x_n = n\(\frac { λ }{ 2 }\) … (7)
where, n = 0, 1, 2, …
For n = 0 we have minimum at
x_o = 0
For n = 1 we have minimum at
x₁ = \(\frac { λ }{ 2 }\)
For n = 2 we have maximum at
x₂ = λ
and so on.
The distance between any two successive nodes can be calculated as
x_n – x_n-1 – n\(\frac { λ }{ 2 }\) – (n-1)\(\frac { λ }{ 2 }\) = \(\frac { λ }{ 2 }\)

Characteristics of stationary waves:

• Stationary waves are characterized by the confinement of a wave disturbance between two rigid boundaries. It is meant that the wave does not move forward or backward in a medium (does not advance), it remains steady at its place. Hence, they are called “stationary waves or standing waves”.
• Certain points in the region in which the wave exists have maximum amplitude, called anti-nodes. At certain points, the amplitude is minimum or zero, called nodes.
• The distance between two consecutive nodes (or) anti-nodes is \(\frac { λ }{ 2 }\).
• The distance between a node and its neighboring anti-node is \(\frac { λ }{ 4 }\).
• The transfer of energy along the standing wave is zero.

Question 10.
Discuss the law of transverse vibrations in stretched strings.
Answer:
There are three laws of transverse vibrations of stretched strings that are given as follows:
(i) The law of length: For a given wire with tension T (which is fixed) and mass per unit length µ. (fixed) the frequency varies inversely with the vibrating length. Therefore,
f ∝ \(\frac { 1 }{ f }\) ⇒ f = \(\frac { C }{ l }\)
⇒ l x f = C, when C is a constant.

(ii) The law of tension: For a given vibrating length l (fixed) and mass per unit length µ (fixed) the frequency varies directly with the square root of the tension T,
f ∝ \(\sqrt{T}\)
⇒ f = A\(\sqrt{T}\), when A is a constant.

(iii) The law of mass: For a given vibrating length l (fixed) and tension T (fixed) the frequency varies inversely with the square root of the mass per unit length μ,
f ∝ \(\frac{1}{\sqrt{\mu}}\) when B is a constant.

Question 11.
Explain the concepts of frequency, harmonics and detail.
Answer:
(i) The fundamental frequency is the lowest natural frequency.

(ii) If natural frequencies are written as integral multiples of the fundamental frequency, then the frequencies are said to be in harmonics. So, the first harmonic is v₁ = v₁, (the fundamental frequency is called first harmonics), the second harmonics is v₂ = 2v₁ the third harmonics is v₃ = 3v_1, and so on.

(iii) The frequency higher than the fundamental frequency can be produced by blowing air strongly at the open end. Such frequencies are called overtones.

First overtone, (f₂ = 3f₁) since here, the frequency is three times the fundamental frequency it is called third harmonic. Second overtone, (f₃ = 5f₁) and since n = 5 here, this is called fifth harmonic.

Question 12.
What is a sonometer? Give its construction and working. Explain how to determine the frequency of tuning fork using a sonometer.
Answer:
Sonometer is used for sound-related measurements. Using this device, The following quantities can be determined.
(i) The frequency of the tuning fork or frequency of the alternating current.
(ii) The tension in the string.
(iii) The unknown hanging mass.

Construction: The sonometer is made up of a hollow box that is one meter long with a uniform metallic thin string attached to it. One end of the string is connected to a hook and the other end is connected to a weight hanger through a pulley as shown in Figure. Since only one string is used, it is also known as monochord. The weights are added to the free end of the wire to increase the tension of the wire. Two adjustable wooden knives are put over the board, and their positions are adjusted to change the vibrating length of the stretched wire.

Procedure: A transverse stationary or standing wave is produced. So, at the knife edges P and Q, nodes are formed. In between the knife edges, anti-nodes are formed.
If the length of the vibrating element is l then
l = \(\frac { λ }{ 2 }\) ⇒ λ = 2l
Let f be the frequency of the vibrating element, T the tension in the string, and p the mass per unit length of the string.
Then using the the equation v = \(\sqrt{\frac{\mathrm{T}}{\mu}}\) measured in ms^-1, we get,
f = \(\frac { v }{ λ }\) = \(\frac { 1 }{ 2l }\)\(\sqrt{\frac{\mathrm{T}}{\mu}}\) in Hertz.
Let ρ be the density of the material of the string and d be the diameter of the string. Then the mass per unit length μ,

Question 13.
Write short notes on intensity and loudness.
Answer:
The intensity of sound is defined as “the sound power transmitted per unit area taken normal to the propagation of the sound wave”. The intensity of sound is inversely proportional to the square of the distance from the source.

This is known as the inverse square law of sound intensity. Two sounds with the same intensities need not have the same loudness. For example, the sound heard during the explosion of balloons in a silent closed room is very loud when compared to the same explosion happening in a noisy market.

If the intensity of sound is increased then loudness also increases. Loudness depends on both intensities of the sound wave and sensitivity of the ear.

Question 14.
Explain how overtones are produced in a,
(a) closed organ pipe
(b) Open organ pipe
Answer:
(a) Closed organ pipes: If one end of a pipe is closed, the wave reflected at this closed-end is 180° out of phase with the incoming wave. So, there is no displacement of the particles at the closed end. Hence, nodes are formed at the closed end and anti-nodes are formed at the open end.

Consider the simplest mode of vibration of the air column called the fundamental mode. Anti-node is formed at the open end and node at the closed end. From the above figure, let L be the length of the tube and the wavelength of the wave produced. For the fundamental mode of vibration, we have,
– L = \(\frac{\lambda_{1}}{4}\) (or)
Wave length λ₁ = 4L
The frequency of the note emitted is
f₁ = \(\frac{v}{\lambda_{1}}\) = \(\frac { v }{ 4L }\)
which is called the fundamental note.
The frequencies higher than the fundamental frequency can be produced by blowing air strongly at the open end. Such frequencies are called overtones.
The second mode of vibration in open pipes is shown in the figure.

is called the first overtone, since here, the frequency is three times the fundamental frequency it is called third harmonic. The Figure shows the third mode of vibration having three nodes and three anti-nodes.

is called the second overtone, and since n = 5 here, this is called fifth harmonic. Hence, the closed organ pipe has only odd harmonics and the frequency of the n^th harmonic is f_n = (2n+l)f₁. Hence, the frequencies of harmonics are in the ratio,
f₁ : f₂ : f₃ : f₄ = 1 : 3 : 5 : 7 : …

(b) Open organ pipes:
The flute is an example of an open organ pipe. It is a pipe with both ends are opened. At both open ends, anti-nodes are formed. Consider the simplest mode of vibration of the air column called fundamental mode. Since anti-nodes are formed at the open end, a node is formed at the mid-point of the pipe.

From above Figure, if L be the length of the tube, the wavelength of the wave produced is given by
L=\(\frac{\lambda_{1}}{2}\) (or) λ₁ = 2L
The frequency of the note emitted is
f₁ = \(\frac{v}{\lambda_{1}}\) = \(\frac { v }{ 2L }\)
That is called the fundamental note.
The frequencies higher than the fundamental frequency can be produced by blowing air strongly at one of the open ends. Such frequencies are called overtones.

The second mode of vibration in open pipes is shown in figure. It has two nodes and three anti-nodes,
∴ L = λ₂ (or) λ₂ = L
The frequency,
f₂ = \(\frac{v}{\lambda_{2}}\) = \(\frac { v }{ L }\) = 2 x \(\frac { v }{ 2L }\) = 2f₁
is called first over tone. Since n = 2 here, it is called the second harmonic.

The Figure above shows the third mode of vibration having three nodes and four anti-nodes
∴ L = \(\frac { 3 }{ 2 }\)λ₃ (or) λ₃ = \(\frac { 2L }{ 3 }\)
The frequency,
f₃ = \(\frac{v}{\lambda_{3}}\) = \(\frac { 3v }{ 2L }\) = 3₁
is called second over tone. Since n = 3 here, it is called the third harmonic.
Hence, the open organ pipe has all the harmonics, and the frequency of the n^th harmonic is f_n = nf₁.
Hence, the frequencies of harmonics are in the ratio f₁ : f₂ : f₃ : f₄ = 1 : 2 : 3 : 4 : …

Question 15.
How will you determine the velocity of sound using the resonance air column apparatus?
Answer:

The resonance air column apparatus is used to measure the speed of sound in air at room temperature.

Construction:
(i) It consists of a cylindrical glass tube of one-meter length whose one end A is open and another end B is connected to the water reservoir R through a rubber tube as shown in Figure.

(ii) This cylindrical glass tube is mounted on a vertical stand with a scale attached to it. The tube is partially filled with water and the water level can be adjusted by raising or lowering the water in the reservoir R.

(iii) The surface of the water will act as a closed-end and others as the open end. Hence, it behaves like a closed organ pipe, forming nodes at the surface of water and antinodes at the closed end.

(iv) When a vibrating tuning fork is brought near the open end of the tube, longitudinal waves are formed inside the air column.

(v) These waves move downward as shown in Figure, and reach the surfaces of water and get reflected and produce standing waves.

(vi) The length of the air column is varied by changing the water level until a loud sound is produced in the air column.

(vii) At this particular length the frequency of waves in the air column resonates with the frequency of the tuning fork (natural frequency of the tuning fork).

(viii) At resonance, the frequency of sound waves produced is equal to the frequency of the tuning fork. This will occur only when the length of the air column is proportional to (\(\frac { 1 }{ 4 }\))^th of the wavelength of the sound waves produced. \(\frac { 1 }{ 4 }\)λ = L₁ … (1)
But since the antinodes are not exactly formed at the open end, a Correction is to include. It is called end correction e, by assuming that the antinode is formed at some small distance above the open end. Including this end correction, the first resonance is \(\frac { 1 }{ 4 }\)λ = L₁ + e … (2)
Now the length of the air column is increased to get the second resonance. Let L₂ be the length at which the second resonance occurs. Again taking end correction into account, we have
\(\frac { 3 }{ 4 }\)λ = L₂ + e … (3)
In order to avoid end correction, let us make the difference of equation (3) and equation (2), we get
\(\frac { 3 }{ 4 }\)λ – \(\frac { 1 }{ 4 }\)λ = (L₂ + e) – (L₁ + e)
⇒ \(\frac { 1 }{ 2 }\)λ = L₂ – L₁ = ∆L
⇒ λ = 2∆L
The speed of the sound in air at room temperature can be calculated by using the formula
v = fλ = 2f∆L.

Question 16.
What is meant by the Doppler effect? Discuss the following cases.
(i) Source in motion and Observer at rest

• Source moves towards the observer
• Source moves away from the observer

(ii) Observer in motion and Source at rest.

• The observer moves towards Source
• Observer resides away from the Source

(iii) Both are in motion

• Source and Observer approach each other
• Source and Observer resides from each other
• Source chases Observer
• Observer chases Source

Answer:
When the source and the observer are in relative motion with respect to each other and to the medium in which sound is propagated, the frequency of the sound wave observed is different from the frequency of the source. This phenomenon is called Doppler Effect.

(i) Source in motion and the observer at rest:
(a) Source moves towards die observer:

Suppose a source S moves to the right (as shown in Figure) with a velocity v_s and let the frequency of the sound waves produced by the source be f_s. It is assumed that the velocity of sound in a medium is v.

The compression (sound wavefront) produced by the source S at three successive instants of time are shown in the Figure. When S is at position x₁ the compression is at C₁. When S is at position x₂, the compression is at C₂ and similarly for x₃ and C₃.

It is assumed that if C₁ reaches the observer’s position A then at that instant C₂ reaches point B and C₃ reaches point C as shown in the Figure. Obviously it is seen that the distance between compressions C₂ and C₃ is shorter than the distance between C₁ and C₂.

It is meant that the wavelength decreases when the source S moves towards the observer O. But frequency is inversely related to wavelength and therefore, frequency increases.
Calculation:
Let λ be the wavelength of the source S as measured by the observer when S is at position x₁ and λ’ be the wavelength of the source observed by the observer when S moves to position x₂.

Then the change in wavelength is ∆λ = λ – λ’ = v_st, where t is the time taken by the source to travel between x₁ and x₂ Therefore,
λ’ = λ – v_st … (1)
But t = \(\frac { λ }{ v }\) … (2)
On substituting equations (2) in equation (1), we get.
λ’ = λ(1 – \(\frac{v_{s}}{v}\))
Since frequency is inversely proportional to wavelength, we have

Since, \(\frac{v_{s}}{v}\) << 1, by using the binomial expansion and retaining only first order in \(\frac{v_{s}}{v}\), we get
f ‘ = f(1 + \(\frac{v_{s}}{v}\)) … (4)

(b) Source moves away from the observer Since the velocity of the source is opposite in direction when compared to case (a), hence by changing the sign of the velocity of the source in the above case i.e., by substituting (v_s → – v ) in equation (1), we get
f ‘= \(\frac{f}{\left(1+\frac{v_{s}}{v}\right)}\) … (5)
Using binomial expansion again, we get
f ‘= f(1 – \(\frac{v_{s}}{v}\)) … (6)

(ii) Observer in motion and source at rest:
(a) Observer moves towards Source:

We can assume that the observer O moves towards the source S with velocity v_o. The source S is at rest and the velocity of sound waves (with respect to the medium) produced by the source is v.
From the Figure, It is observed that both v_o and v are in opposite direction. Then, their relative velocity is v_r = v + v_o. The wavelength of the sound wave is λ = \(\frac { v }{ f }\), which means the frequency observed by the observer O is f ‘ = \(\frac{v_{r}}{\lambda}\). Then

(b) Observer recedes away from the Source: If the observer O is moving away (receding away) from the source S, then velocity v₀ and v move in the same direction. Hence, their relative velocity is v_r = v – v₀. Hence, the frequency observed by the observer O is

(iii) Both are in motion:
(a) Source and observer approach each other:

Let v_s and v_o be the respective velocities of source and observer approaching each other as shown in Figure. In order to calculate the apparent frequency observed by the observer, let us have a dummy (behaving as observer or source) in between the source and observer. Since the dummy is at rest, the dummy (observer) observes the apparent frequency due to approaching source as given in equation f ‘ =\(\frac{f}{\left(1-\frac{v_{s}}{v}\right)}\)
f_d = \(\frac{f}{\left(1-\frac{v_{s}}{v}\right)}\) … (1)
The true observer approaches the dummy from the other side at that instant of time. Since the source (true source) comes in a direction opposite to the true observer, the dummy (source) is treated as a stationary source for the true observer at that instant. Hence, apparent frequency when the true observer approaches the stationary source (dummy source), f’ = f(1 + \(\frac{v_{0}}{v}\)).

Since this is true for any arbitrary time, therefore, comparing equation (1) and equation (2), we get

(b) Source and observer recede from each other:

It is noticed that the velocity of the source and the observer each point in opposite directions with respect to the case in (a) and hence, we substitute (v_s → – v_s) and (v₀ → – v₀) in equation (3), and therefore, the apparent frequency observed by the observer when the source and observer recede from each other is f’ = \(\left(\frac{v-v_{0}}{v+v_{s}}\right)\)f

(c) Source chases the observer:

Only the observer’s velocity is oppositely directed when compared to case (a). Therefore, substituting (v₀ → – v₀) in equation (3), we get f’ = \(\left(\frac{v-v_{0}}{v-v_{s}}\right)\)f

(d) Observer chases the source:

Only the source velocity is oppositely directed when compared to case (a). Therefore, substituting (v_s → – v_s) in equation (3), we get f’ = \(\left(\frac{v+v_{0}}{v+v_{s}}\right)\)f

IV. Numerical Problems:

Question 1.
The speed of a wave in a certain medium is 900 m/s. If 3000 waves pass over a certain point of the medium in 2 minutes, then compute its wavelength?
Answer:
Given:

Question 2.
Consider a mixture of 2 mol of helium and 4 mol of oxygen. Compute the speed of sound in this gas mixture at 300 K.
Answer:
Number of molecules of helium = 2
Number of molecules of oxygen = 4
When helium and oxygen are mixed, hence the molecular weight of the mixture of gases is given by

In addition, helium is monoatomic,
\(\mathrm{C}_{v_{2}}\) = \(\frac { 2R }{ 2 }\)
Oxygen is diatomic \(\mathrm{C}_{v_{1}}\) = \(\frac { 5R }{ 2 }\)

Ratio of specific heat capacitors of a mixture of gases is

According to Laplace, the speed of sound in a gas is

∴ The speed of sound = 400.9 m/s

Question 3.
A ship in a sea sends SONAR waves straight down into the seawater from the bottom of the ship. The signal reflects from the deep bottom bedrock and returns to the ship after 3.5 s. After the ship moves to 100 km it sends another signal which returns back after 2 s. Calculate the depth of the sea in each case and also compute the difference in height between two cases.
Answer:
In the first case
time = 3.5s
Velocity sound in sea water = 1450 m/s
Distance 2d = v x t
= 1450 x 3.5 = 5,075 m
Depth of the sea d = \(\frac { 5075 }{ 2 }\) = 2537.5 m
In the second case,
time = 2s
Velocity of sound in water = 1450 m/s
Distance 2d = vt
= 1450 x 2
= 2900 m
Depth of the sea d = \(\frac { 2900 }{ 2 }\) = 1450
Difference ∆d = 2537.5 – 1450 = 1087.5
= 1087.5 m

Question 4.
A sound wave is transmitted into a tube as shown in the figure. The sound wave splits into two waves at point A which recombine at point B. Let R be the radius of the semi-circle which is varied until the first minimum. Calculate the radius of the semi-circle if the wavelength of the sound is 50.0 m.
Answer:

Path difference = πR – 2R
[Here AB = 2R; Semicircle path = πR]
Formula:
Path difference = (2n – 1)\(\frac { λ }{ 2 }\) (for minimum n – 1)

Question 5.
N tuning forks are arranged in order of increasing frequency and any two successive tuning forks give n beats per second when sounded together. If the last fork gives double the frequency of the first (called as octave), Show that the frequency of the first tuning fork is f = (N – 1)n.
Answer:
f,f + n,f+ 2n, … f + (m – 1)n
f + (N – 1)n = 2f
n = \(\frac { f }{ N-1 }\)
(or) f = n(N – 1)

Question 6.
Let the source propagate a sound wave whose intensity at a point (initially) be I. Suppose we consider a case when the amplitude of the sound wave is doubled and the frequency is reduced to one-fourth. Calculate now the new intensity of sound at the same point?
Answer:
Given:

Question 7.
Consider two organ pipes of the same length in which one organ pipe is closed and another organ pipe is open. If the fundamental frequency of closed pipe is 250 Hz. Calculate the fundamental frequency of the open pipe.
Answer:

Formula:

Question 8.
Police in a siren car moving with a velocity of 20 ms^-1 chases a thief who is moving in a car with a velocity v₀ms^-1. The police car sounds at frequency 300 Hz, and both of them move towards a stationary siren of frequency 400 Hz. Calculate the speed at which the thief is moving.
Answer:
Velocity of sound v = 330 m/s
Velocity of a police siren car v_s = 20 m/s
Frequency of a police siren car f = 300 Hz
Let the velocity of the thief be v m/s
The frequency of police siren heard by a thief is
f₁ = \(\left(\frac{330-v}{330-20}\right)\) x 300
= \(\left(\frac{330-v}{310}\right)\) x 300 Hz
Frequency of stationary siren = 400 Hz
Frequency of stationaiy siren heard by a thief
f₂ = \(\left(\frac{330+v}{330}\right)\) x 400
If there are no beats then

Question 9.
Consider the following function,
(a) y = x² + 2 α tx
(b) y = (x + vt)²
which among the above function can be characterized as a wave?
Answer:
Given:
Formula:
For the function to be a wave function \(\frac { (dy/dx) }{ (dy/dt) }\) should be a constant.
For function (a):

Hence, function
(a) does not describe a wave.
(b) satisfies wave function.

V. Conceptual Questions:

Question 1.
Why is it that transverse waves cannot be produced in a gas? Can the transverse waves be produced in solids and liquids?
Answer:
They travel in the form of crests and troughs and so involve a change in shape. They can be produced in a medium that has elasticity in shape. As gas has no elasticity of shape, hence transverse waves cannot be produced in a gas. Transverse waves can be produced in solids anion the surface of liquids.

Question 2.
Why is the roar of our national animal different from the sound of a mosquito?
Answer:
The pitch of the sound of our national animal lion is higher than that of mosquitoes. In addition, the frequency of sound waves generated by our national animal is more than the frequency of sound waves generated by mosquitoes.

Question 3.
A sound source and listener are both stationary and a strong wind is blowing. Is there a Doppler effect?
Answer:
When both source and listener are stationary, there is no relative motion between the source and the observer. Hence there is no Doppler effect.

Question 4.
In an empty room, why is it that a tone sounds louder than in the room having things like furniture, etc.
Answer:
When a room has furniture reverberation time can be suitably decreased since furniture has a large absorption coefficient of sound. So a tone sounds with lesser amplitude and intensity. Whereas in an empty room, reverberation time will be more than a room having things like furniture.

Question 5.
How do animals sense the impending danger of hurricanes?
Answer:
Hurricane produces a shock wave which has a speed greater than the speed of sound. It travels with a supersonic sound that can be easily sensed by animals using the Doppler effect. The multiple reflections of sound can be easily sensed by animals.

Question 6.
Is it possible to realize whether a vessel kept under the tap is about to fill with water?
Answer:
Yes. The frequency of a note generated by an air column is inversely proportional to its length. Consequently, as the length of the air column decreases, the frequency increases, i.e., the note becomes more shrill. In our case, when a vessel kept under the top is about to fill with water, as the water level rises, the length of the air column in the vessel goes on decreasing and the emitted sound becomes more and more shrill. Hence it is realised.

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Computer Science Guide Pdf Chapter 17 Computer Ethics and Cyber Security Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Computer Science Solutions Chapter 17 Computer Ethics and Cyber Security

11th Computer Science Guide Computer Ethics and Cyber Security Text Book Questions and Answers

Part -I

Choose The Correct Answer

Question 1.
Which of the following deals with procedures, practices and values?
a) piracy
b) programs
c) virus
d) computer ethics
Answer:
d) computer ethics

Question 2.
Commercial programs made available to the public illegally are known as
a) freeware
b) warez
c) free software
d) software
Answer:
b) warez

Question 3.
Which one of the following are self-repeating and do npt require a computer program to attach themselves?
a) viruses
b) worms
c) spyware
d) Trojans
Answer:
b) worms

Question 4.
Which one of the following tracks a user visits a website?
a) spyware
b) cookies
c) worms
d) Trojans
Answer:
b) cookies

Question 5.
Which of the following is not a malicious program on computer systems?
a) worms
d) Trojans
c) spyware
d) cookies
Answer:
d) cookies

Question 6.
A computer network security that monitors and controls incoming and outgoing traffic is
a) Cookies
b) Virus
c) Firewall
d) worms
Answer:
c) Firewall

Question 7.
The process of Converting cipher text to plain text is called
a) Encryption
b) Decryption
c) key
d) proxy server
Answer:
b) Decryption

Question 8.
e-commerce means
a) electronic commerce
b) electronic data exchange
c) electric data exchange
d) electronic commercialization.
Answer:
a) electronic commerce

Question 9.
Distributing unwanted e-mail to others is called
a) scam
b) spam
c) fraud
d) spoofing
Answer:
b) spam

Question 10.
Legal recognition for transactions are carried out by
a) Electronic Data Interchange
b) Electronic Data Exchange
c) Electronic Data Transfer
d) Electrical Data Interchange
Answer:
a) Electronic Data Interchange

Part – II

Very Short Answers

Question 1.
What is harvesting?
Answer:
A person or program collects login and password information from a legitimate user to illegally gain access to others account(s).

Question 2.
What are Warez?
Answer:
Commercial programs that are made available to the public illegally are often called warez.

Question 3.
Write a short note on cracking.
Answer:
Cracking is where someone edits a program source so that the code can be exploited or modified. “Cracking” means trying to get into computer systems in order to steal, corrupt, or illegitimately view data.

Question 4.
Write two types of cyber attacks.
Answer:
The following are cyber attacks:

• Virus
• Worms
• Spyware
• Ransomware

Question 5.
What is a Cookie?
Answer:
A cookie (also called HTTP cookie, web cookie, Internet cookie, browser cookie, or simply cookie) is a small piece of data sent from a website and stored on the user’s computer memory (Hard drive) by the user’s web browser while the user is browsing the internet.

Part – III

Short Answers

Question 1.
What is the role of firewalls?
Answer:
Role of firewalls:

• A firewall is a computer network security based system that monitors and controls incoming and outgoing network traffic based on predefined security rules.
• A firewall commonly establishes a block between a trusted internal computer network and entrusted computer outside the network.

Question 2.
Write about encryption and decryption.
Answer:
Encryption and decryption are processes that ensure confidentiality that only authorized persons can access the information. Encryption is the process of translating plain text data (plaintext) into random and mangled data (called ciphertext). Decryption is the reverse process of converting the ciphertext back to plaintext. Encryption and decryption are done by cryptography. In cryptography, a key is a piece of information (parameter) that determines the functional output of a cryptographic algorithm.

Question 3.
Explain symmetric key encryption.
Answer:
SYMMETRIC KEY ENCRYPTION:
Symmetric encryption is a technique to use the same key for both encryption and decryption.

The main disadvantage of symmetric key encryption is that all authorized persons involved, have to exchange the key used to encrypt the data before they can decrypt it. If anybody intercepts the key information, they may read all messages.
The following Figure depicts the working of symmetric key encryption.

Question 4.
What are the guidelines to be followed by any computer user?
Answer:
Generally, the following guidelines should be observed by computer users:

1. Honesty: Users should be truthful while using the internet.
2. Confidentiality: Users should not share any important information with unauthorized people.
3. Respect: Each user should respect the privacy of other users.
4. Professionalism: Each user should maintain professional conduct.
5. Obey The Law: Users should strictly obey the cyber law in computer usage.
6. Responsibility: Each user should take ownership and responsibility for their actions.

Question 5.
What are ethical issues? Name some of them.
Answer:
An Ethical issue is a problem or issue that requires a person or organization to choose between alternatives that must be evaluated as right (ethical) or wrong (unethical). These issues must be addressed and resolved to have a positive influence in society.

Some of the common ethical issues are listed below:

• Cyber crime
• Software Piracy
• Unauthorized Access
• Hacking
• Use of computers to commit fraud
• Sabotage in the form of viruses
• Making false claims using computers

Part IV

Explain in Detail

Question 1.
What are the various crimes happening using computers?
Answer:
Cyber Crime:
Cyber crime is an intellectual, white-collar crime. Those who commit such crimes generally manipulate the computer system in an intelligent manner. For example – illegal money transfer via the internet.

Examples of some Computer crimes and their functions are listed below in the following Table :

Question 2.
What is piracy? Mention the types of piracy? How can it be prevented?
Answer:
Software Piracy:
Software Piracy is about the copyright violation of software created originally by an individual or an institution. It includes stealing codes/programs and other information illegally and creating duplicate copies by unauthorized means and utilizing this data either for one’s own benefit or for commercial profit.

In simple words, Software Piracy is “unauthorized copying of software*’. The following Figure shows a diagrammatical representation of software piracy.

Types Of Piracy:

Shareware: An entirely different approach to software piracy is called shareware, which acknowledges the futility of trying to stop people from copying software and instead relies on people’s honesty.

Warez: Commercial programs that are made available to the public illegally are often called warez.

Prevention Method:

• Illegal copying and distribution of commercial software should not be practiced.
• Shareware publishers encourage users to give copies of programs to friends and colleagues but ask everyone who uses that program regularly to pay a registration fee to the program’s author directly.

Question 3.
Write the different types of cyber attacks.
Answer:
Types Of Cyber Attacks:
Malware is a type of software designed through which criminals gain illegal access to software and cause damage. Various types of cyber-attacks and their functions are given in the following Table.

11th Computer Science Guide Computer Ethics and Cyber Security Additional Questions and Answers

Part I

Choose The Correct Answer

Question 1.
A moral code that is evaluated as right is ………………..
(a) piracy
(b) viruses
(c) cracking
(d) ethics
Answer:
(d) ethics

Question 2.
Information Technology is widespread through ________
a) Computers
b) Mobile phones
c) Internet
d) All the above
Answer:
d) All the above

Question 3.
Stealing data from a computer system without knowledge or permission is called ………………..
(a) warez
(b) hacking
(c) cracking
(d) phishing
Answer:
(b) hacking

Question 4.
A(n) ________ is a crime which involves computer and network.
a) Cyber-crime
b) Ethics
c) Cyber-law
d) None of these
Answer:
a) Cyber-crime

Question 5.
……………….. is the intermediary between the end-users and a web browser.
(a) Firewall
(b) Proxy server
(c) Cookies
(d) Warez
Answer:
(b) Proxy server

Question 6.
________ is a cybercrime.
a) Phishing
b) Hacking
c) Identity thefts
d) All the above
Answer:
d) All the above

Question 7.
________ is a cybercrime.
a) Pharming
b) Piracy
c) Online financial transaction
d) All the above
Answer:
d) All the above

Question 8.
Ethics means________
a) What is wrong
b) What is Right
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 9.
________ is a set of moral principles that rule the behavior of individuals who use computers,
a) Ethics
b) Cyber-Crime
c) Virus
d) None of these
Answer:
a) Ethics

Question 10.
An individual gains knowledge to follow the right behavior, using morals that are also known as________
a) Ethics
c) Phishing
c) Hacking
d) None of these
Answer:
a) Ethics

Question 11.
________ refer to the generally accepted standards of right and wrong in the society,
a) Piracy
b) Morals
c) Virus
d) None of these
Answer:
b) Morals

Question 12.
________ is a cyber world standard.
a) Do not use pirated software
b) Do not hack
c) Do not steal others’ passwords
d) All the above
Answer:
b) Do not hack

Question 13.
________ is a guidelines of computer ethics.
a) Honesty
b) Confidentiality
c) Respect
d) All the above
Answer:
d) All the above

Question 14.
________ is a guidelines of computer ethics.
a) Professionalism
b) Obey the law
c) Responsibility
d) All the above
Answer:
d) All the above

Question 15.
Identify the correct statement from the following.
a) Ethics is a set of moral principles that govern the behavior of an individual in a society.
b) Computer ethics is set of moral principles that regulate the use of computers by users.
c) An Ethical issue is a problem or issue that requires a person or organization to choose between alternatives that must be evaluated as right or wrong.
d) All the above
Answer:
d) All the above

Question 16.
Identify the correct statement from the following related to ethics.
a) Users should be truthful while using the internet.
b) Users should not share any important information with unauthorized people.
c) Each user should respect the privacy of other users.
d) All the above
Answer:
d) All the above

Question 17.
Identify the correct statement from the following related to ethics.
a) Each user should maintain a professional conduct.
b) Users should strictly obey the cyber law in computer usage.
c) Each user should take ownership and responsibility for their actions
d) All the above
Answer:
d) All the above

Question 18.
Cybercrime is a(n) ________ crime.
a) Intellectual
b) White-collar
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 19.
Harassing through online is called ________
a) Cyber Stalking
b) Cyber Harassment
c) Cyber torture
d) None of these
Answer:
a) Cyber Stalking

Question 20.
________ are malicious programs that can perform a variety of functions on user’s computer activity without their permission.
a) Cyber Stalking
b) Malware
c) Antivirus
d) None of these
Answer:
b) Malware

Question 21.
Malicious programs that can perform a variety of functions including ________ on user’s Computer activity without their permission.
a) Encrypting or Deleting sensitive data
b) Stealing
c) Hijacking core computing functions
d) All the above
Answer:
d) All the above

Question 22.
Overloading a system with fake requests so that it cannot serve normal legitimate requests is called________
a) Cyber Stalking
b) Malware
c) Denial of service attack
d) None of these
Answer:
c) Denial of service attack

Question 23.
Manipulating data like changing the banking records to transfer money to an unauthorized account is called ________
a) Cyber Stalking
b) Malware
c) Denial of service attack
d) Fraud
Answer:
d) Fraud

Question 24.
________ means a person or program collects login and password information from a legitimate user to illegally gain access to others accounts.
a) Harvesting
b) Malware
c) Denial of service attack
d) Fraud
Answer:
a) Harvesting

Question 25.
________ is a crime where the criminals impersonate individuals, usually for financial gain.
a) Harvesting
b) Identity theft
c) Denial of service attack
d) Fraud
Answer:
b) Identity theft

Question 26.
________ means stealing practical or conceptual information developed by another person or company.
a) Harvesting
b) Identity theft
c) Intellectual property theft
d) Fraud
Answer:
c) Intellectual property theft

Question 27.
________ meant tricking people into believing something that is not true.
a) Harvesting
b) Scam
c) Intellectual property theft
d) Fraud
Answer:
b) Scam

Question 28.
Stealing tiny amounts of money from each transaction means ________
a) Salami slicing
b) Scam
c) Intellectual property theft
d) Fraud
Answer:
a) Salami slicing

Question 29.
Distribute unwanted e-mail to a large number of internet is termed as ________
a) Salami slicing
b) Scam
c) Intellectual property theft
d) Spam
Answer:
d) Spam

Question 30.
________ is a malicious practice in which communication is send from unknown source disguised as a source known to the receiver.
a) Salami slicing
b) Scam
c) Spoofing
d) Spam
Answer:
c) Spoofing

Question 31.
Software________ is about the copyright violation of software created originally by an individual or an institution.
a) Piracy
b) Fraud
c) Theft
d) None of these
Answer:
a) Piracy

Question 32.
________ includes stealing of codes / programs and other information illegally and creating duplicate copies by unauthorized means and utilizing this data either for one’s own benefit or for commercial profit.
a) Piracy
b) Scam
c) Salami slicing
d) None of these
Answer:
a) Piracy

Question 33.
To prevent unauthorized access ________ is used.
a) Firewalls/ Intrusion Detection Systems
b) Virus and Content Scanners
c) Patches and Hotfixes
d) All the above
Answer:
d) All the above

Question 34.
IDS means.________
a) Intrusion Detection Systems
b) Intrusion Defective Systems
c) Intrusion Direction Systems
d) Intrusion Detach Systems
Answer:
a) Intrusion Detection Systems

Question 35.
________ is intruding into a computer system to steal personal data without the owner’s permission or knowledge.
a) Piracy
b) Hacking
c) IDS
d) None of these
Answer:
b) Hacking

Question 36.
Steal a password is________
a) Piracy
b) Hacking
c) IDS
d) None of these
Answer:
b) Hacking

Question 37.
________ is where someone edits a program source so that the code can be exploited or modified.
a) Piracy
b) Hacking
c) Cracking
d) None of these
Answer:
c) Cracking

Question 38.
A cracker is called as a ________
a) Black hat
b) Dark side hacker
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 39.
Cracking means trying to get into computer systems in order to________ data.
a) Steal
b) Corrupt
c) Illegitimately view
d) All the above
Answer:
d) All the above

Question 40.
A ________ is someone who breaks into someone else’s computer system, often on a network, bypassing passwords or licenses in computer programs.
a) Cracker
b) Programmer
c) Server
d) None of these
Answer:
a) Cracker

Question 41.
Password cracking can be performed by________
a) Using an automated program
b) Can be manually realized
c) Either A or B
d) None of these
Answer:
c) Either A or B

Question 42.
IRC means ________
a) International Relay Chat
b) Internet Relay Chat
c) Internal Relay Chat
d) Internet Ready Chat
Answer:
b) Internet Relay Chat

Question 43.
The method that uses social engineering crackers is ________ guessing.
a) Password
b) Username
c) Website name
d) URL
Answer:
a) Password

Question 44.
Identify the correct statement from the following related with cracking.
a) It is a method of getting passwords and information using human weakness.
b) Crackers find your personal information from some persona! data/facts and try to guess a password.
c) Crackers may send official e-mail requesting some sensitive information. It may look like a legitimate e-mail from bank or other official institution.
d) All the above
Answer:
d) All the above

Question 45.
________ is a collection of various technologies, processes and measures that reduces the risk of cyber attacks.
a) Cyber Security
b) Cyber Crime
c) Cyber Gateway
d) None of these
Answer:
a) Cyber Security

Question 46.
________ protects organizations and individuals from computer based threats.
a) Cyber Security
b) Cyber Crime
c) Cyber Gateway
d) None of these
Answer:
a) Cyber Security

Question 47.
________ is a type of software designed through which the criminals gain iliegal access to software and cause damage.
a) Malware
b) Piracy
c) Cracking
d) None of these
Answer:
a) Malware

Question 48.
A ________ is a small piece of computer code that can repeat itself and spreads from one computer to another by attaching itself to another computer file.
a) Virus
b) Piracy
c) Cracking
d) None of these
Answer:
a) Virus

Question 49.
________ is the most common virus.
a) Trojan
b) Melisa
c) Sasser
d) Code Red
Answer:
a) Trojan

Question 50.
A ________ is a program that appears to perform one function but actually performs malicious activity when executed.
a) Cracking
b) Trojan virus
c) Piracy
d) None of these
Answer:
b) Trojan virus

Question 51.
________ can be installed on the computer automatically when the attachments are open, by clicking on links or by downloading infected software.
a) Spyware
b) Worms
c) Ransomware
d) None of these
Answer:
a) Spyware

Question 52.
________ is a type of malicious program that demands payment after launching a cyber-attack on a computer system.
a) Spyware
b) Worms
c) Ransomware
d) None of these
Answer:
c) Ransomware

Question 53.
________ type of malware has become increasingly popular among criminals and costs the organizations millions each year.
a) Spyware
b) Worms
c) Ransomware
d) None of these
Answer:
c) Ransomware

Question 54.
________ is an example of social engineering.
a) Phishing
b) Pharming
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 55.
Phishing is a type of computer crime used to attack, steal user data, including ________
a) Login name
b) Password
c) Credit card numbers
d) All the above
Answer:
d) All the above

Question 56.
________ occurs when an attacker targets a victim into opening an e-maiior an instant text message.
a) Phishing
b) Pharming
c) Both A and B
d) None of these
Answer:
a) Phishing

Question 57.
________ is a scamming practice in which malicious code is installed on a personal computer or server, misdirecting users to fraudulent web sites without their knowledge or permission.
a) Phishing
b) Pharming
c) Both A and B
d) None of these
Answer:
b) Pharming

Question 58.
Pharming has been called________
a) Phishing without a trap
b) Phishing with a trap
c) Illegal access
d) None of these
Answer:
a) Phishing without a trap

Question 59.
________ is a cyber-attack intended to redirect a website’s traffic to a fake site.
a) Phishing
b) Pharming
c) Trojan
d) None of these
Answer:
b) Pharming

Question 60.
MITM stands for ________
a) Man In The Middle
b) Malware In The Middle
c) Move In The Middle
d) Must In The Middle
Answer:
a) Man In The Middle

Question 61.
________ is an attack where the attacker secretly relays and possibly alters the communication between two parties who believe they are directly communicating With each other.
a) Cyber
b) Man-in-the-middle attack
c) Cracking
d) None of these
Answer:
b) Man-in-the-middle attack

Question 62.
MITM is also called as________
a) Janus attack
b) Junk attack
c) Genious attack
d) None of these
Answer:
a) Janus attack

Question 63.
A ________ is a small piece of data sent from a website and stored on the user’s computer memory (Hard drive) by the user’s web browser while the user is browsing internet,
a) Cookie
b) MITM
c) Cracking
d) Piracy .
Answer:
a) Cookie

Question 64.
A ________ cookie is also called as cookie.
a) HTTP or Web
b) Internet
c) Browser
d) All the above
Answer:
d) All the above

Question 65.
________ can be used to remember arbitrary pieces of information that the user previously entered into form fields such as names, addresses, passwords, and credit card numbers.
a) Cookie
b) MITM
c) Cracking
d) Piracy
Answer:
a) Cookie

Question 66.
An anonymous user is called as________
a) Hacker
b) Malware
c) Cracker
d) None of these
Answer:
a) Hacker

Question 67.
Who can access the cookie information and misuse it?
a) Hacker
b) Service provider
c) Cracker
d) None of these
Answer:
a) Hacker

Question 68.
Web sites typically use cookies for the ________ reason.
a) To collect demographic information about who has visited the Web site.
b) Sites often use this information to track how often visitors come to the site and how long they remain on the site.
c) It helps to personalize the user’s experience on the Web site.
d) All the above
Answer:
d) All the above

Question 69.
________ can help to store personal information about users so that when a user subsequently returns to the site.
a) Cookie
b) MITM
c) Cracking
d) Piracy
Answer:
a) Cookie

Question 70.
________ do not act maliciously on computer system.
a) Virus
b) MITM
c) Cracking
d) Cookie
Answer:
d) Cookie

Question 71.
________ are merely text files that can be deleted at any time.
a) Cookies
b) MITM
c) Cracking
d) Virus
Answer:
a) Cookies

Question 72.
________ cannot be used to spread viruses and they cannot access our hard drive.
a) MITM
b) Cookies
c) Cracking
d) Virus
Answer:
b) Cookies

Question 73.
A ________ commonly establishes a block between a trusted internal computer network and entrusted computer outside the network.
a) Firewall
b) Cookie
c) Hacking
d) None of these
Answer:
a) Firewall

Question 74.
Firewall category is ________
a) Network-based
b) Host-based
c) Either A or B
d) None of these
Answer:
c) Either A or B

Question 75.
________ firewalls are positioned on the gateway computers of LANs [Local Area Network], WANs [Wide Area Network] and intranets.
a) Network-based
b) Host-based
c) Either A or B
d) None of these
Answer:
a) Network-based

Question 76.
________ firewalls are positioned on the network node itself.
a) Network-based
b) Host-based
c) Either A or B
d) None of these
Answer:
b) Host-based

Question 77.
The ________ firewall may be a service as a part of the operating system or an agent application such as endpoint security or protection.
a) Network-based
b) Host-based
c) Either A or B
d) None of these
Answer:
b) Host-based

Question 78.
A ________ acts as an intermediary between the end-users and a web server.
a) Proxy server
b) System software
c) Node
d) None of these
Answer:
a) Proxy server

Question 79.
________ typically keep the frequently visited site addresses in its cache which leads to improved response time.
a) Proxy servers
b) System software
c) Node
d) None of these
Answer:
a) Proxy servers

Question 80.
________ is a process that ensures confidentiality that only authorized persons can access the information.
a) Encryption
b) Decryption
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 81.
________ is the process of translating the plain text data (plaintext) into random and mangled data.
a) Encryption
b) Decryption
c) Sampling
d) None of these
Answer:
a) Encryption

Question 82.
The encrypted text is called________
a) Cybertext
b) Cipher-text
c) Secured text
d) None of these
Answer:
b) Cipher-text

Question 83.
________ is the process of converting the cipher¬text back to plaintext.
a) Encryption
b) Decryption
c) Warping
d) None of these
Answer:
b) Decryption

Question 84.
________ is done by cryptography.
a) Encryption
b) Decryption
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 85.
In cryptography, a ________ is a piece of information that determines the functional output of a cryptographic algorithm.
a) Key
b) Parameter
c) Input
d) Output
Answer:
a) Key

Question 86.
Encryption has been used by ________ to facilitate secret communication.
a) Militaries
b) Governments
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 87.
________ now commonly used in protecting information within many kinds of civilian systems.
a) Encryption
b) Sampling
c) Warping
d) None of these
Answer:
a) Encryption

Question 88.
________ is used to protect data in communication system.
a) Encryption
b) Sampling
c) Warping
d) None of these
Answer:
a) Encryption

Question 89.
Encryption used in ________
a) Data being transferred via networks
b) Mobile telephones
c) Wireless microphones
d) All the above
Answer:
d) All the above

Question 90.
Encryption used in________
a) Wireless intercom systems
b) Bluetooth devices
c) Bank automatic teller machines
d) All the above
Answer:
d) All the above

Question 91.
Data should be ________ when transmitted across networks in order to protect against the network traffic by unauthorized users.
a) Encrypted
b) Translated
c) Converted
d) None of these
Answer:
a) Encrypted

Question 92.
There are________ types of encryption schemes.
a) three
b) four
c) two
d) five
Answer:
c) two

Question 93.
________ is a encryption scheme.
a) Symmetric Key encryption
b) Public Key encryption
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 94.
encryption is a technique to use the same key for both encryption and decryption.
a) Symmetric Key
b) Public Key
c) Either A and B
d) None of these
Answer:
a) Symmetric Key

Question 95.
In________ encryption all authorized persons involved, have to exchange the key used to encrypt the data before they can decrypt it.
a) Symmetric Key
b) Public Key
c) Either A and B
d) None of these
Answer:
a) Symmetric Key

Question 96.
________ encryption is also called Asymmetric encryption
a) Symmetric Key
b) Public Key
c) Both A and B
d) None of these
Answer:
b) Public Key

Question 97.
________ uses the concept of a key-value pair, a different key is used for the encryption and decryption process.
a) Symmetric Key encryption
b) Public Key encryption
c) Both A and B
d) None of these
Answer:
b) Public Key encryption

Question 98.
________ key is used in public key encryption.
a) Private
b) Public
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 99.
The ________ key is kept secret by the owner.
a) Private
b) Public
c) Both A and B
d) None of these
Answer:
a) Private

Question 100.
The ________ key is either shared amongst authorized recipients.
a) Private
b) Public
c) Both A and B
d) None of these
Answer:
b) Public

Question 101.
The data encrypted with the recipient’s ________ key can only be decrypted with the
corresponding key.
a) Public, Private
b) Private, Public
c) Public, Protected
d) None of these
Answer:
a) Public, Private

Question 102.
A digital certificate in a client-server model of communication is one of the example of________
a) Asymmetric Encryption
b) Symmetric
c) Either A or B
d) None of these
Answer:
a) Asymmetric Encryption

Question 103.
A________ is a package of information that identifies a user and a server.
a) Signature
b) Signal
c) Certificate
d) None of these
Answer:
c) Certificate

Question 104.
A certificate contains information such as________
a) An organization’s name
b) The organization that issued the certificate
c) The users’ email address and country and user’s public key
d) All the above
Answer:
d) All the above

Question 105.
Digital signatures are can provide ________ .
a) Assurances of evidence to origin
b) Identity and status of an electronic document, transaction or message
c) Acknowledging informed by the signer
d) All the above
Answer:
d) All the above

Question 106.
________ law is used to prevent cybercrime.
a) Cyber Law or Cyber Space Law
b) Information Technology Law
c) Internet Law
d) Either A or B or C
Answer:
d) Either A or B or C

Question 107.
In India Cyberlaw and IT Act 2000, modified in ________ are being articulated to prevent computer crimes.
a) 2018
b) 2008
c) 1998
d) None of these
Answer:
b) 2008

Question 108.
EDI stands for ________
a) Electronic Data Interchange
b) Electronic Document Interchange
c) Electronic Data Information
d) Electrical Data Interchange
Answer:
a) Electronic Data Interchange

Question 109.
________ is a term that encapsulates the legal issues related to using of the Internet.
a) Cyberlaw
b) Internet law
c) Either A or B
d) None of these
Answer:
c) Either A or B

Question 110.
________ of cybercrime remains unsolved.
a) 75%
b) 50%
c) 25%
d) 10%
Answer:
c) 25%

Question 111.
To protect the information follow________
a) Complex password setting can make your surfing secured.
b) When the internet is not in use, disconnect it.
c) Do NOT open spam mail or emails that have an unfamiliar sender.
d) All the above
Answer:
d) All the above

Question 112.
Identify the correct statement from the following:
a) Information security is the immune system in the body of business.
b) Awareness is the key to security.
c) When using anti-virus software, keep it up-to-date.
d) All the above
Answer:
d) All the above

Part II

Very Short Answers

Question 1.
What is hacking?
Answer:
Hacking is intruding into a computer system to steal personal data without the owner’s permission or knowledge (like to steal a password). It is also gaining unauthorized access to a computer system, and altering its contents.

Question 2.
What is cyber-crime?
Answer:
A cyber-crime is a crime which involves computer and network. This is becoming a growing threat to society and is caused by criminals or irresponsible actions of individuals who are exploiting the widespread use of the Internet.

Question 3.
Mention any 2 reasons as to why the websites use cookies?
Answer:

1. To collect demographic information about who has visited the Web site.
2. It helps to personalize the user’s experience on the Website.

Question 4.
What are the types of Cybercrime?
Answer:
It is depicted in the following diagram:

Question 5.
Define software piracy.
Answer:
Software Piracy is about the copyright violation of software created originally by an individual or an institution. It includes stealing codes/programs and other information illegally and creating duplicate copies by unauthorized means and utilizing this data either for one’s own benefit or for commercial profit.

Question 6.
What are the standards in the cyber-world?
Answer:
In the cyber-world, there are certain standards such as:

• Do not use pirated software.
• Do not use unauthorized user accounts.
• Do not steal others’ passwords.
• Do not hack.

Question 7.
What are the core issues in computer ethics?
Answer:
The core issues in computer ethics are based on the scenarios arising from the use of the internets such as privacy, the publication of copyrighted content, unauthorized distribution of digital content, and user interaction with websites, software, and related services.

Question 8.
What are the changes in society due to the internet?
Answer:

• With the help of the internet, the world has now become a global village.
• The Internet has been proven to be a boon to individuals as well as various organizations and businesses.
• e-Commerce is becoming very popular among businesses as it helps them to reach a wide range of customers faster than any other means;

Question 9.
What are the roles of computer ethics?
Answer:
Computer ethiŒ deals with the proœdures, values, and practices that govern the process of consuming computer technology and its related disciplines without damaging or violating the moral values and beliefs of any individual, organization, or entity.

Question 10.
What is the difference between ethics and computer ethics?
Answer:

• Ethics is a set of moral principles that govern the behavior of an individual in a society.
• Computer ethics is set of moral principles that regulate the use of computers by users.

Question 11.
What is cybercrime? Give an example.
Answer:
Cyber Crime
Cybercrime is an intellectual, white-collar crime. Those who commit such crimes generally manipulate the computer system in an intelligent manner.
For example – illegal money transfer via the internet.

Question 12.
How to prevent unauthorized access?
Answer:
To prevent unauthorized access, Firewalls, Intrusion Detection Systems (IDS), Virus and Content Scanners, Patches and Hotfixes are used.

Question 13.
What is social engineering? Give an example.
Answer:
Social engineering
A misuse of an individual’s weakness, achieved by making them to click malicious links, or by physically accessing the computer through tricks. Phishing and pharming.

Question 14.
What are Cookies?
Answer:
A cookie is a small piece of data sent from a website and stored on the user’s computer memory (Hard drive) by the user’s web browser while the user is browsing the internet.

Question 15.
What are the types of encryption?
Answer:
There are two types of encryption schemes as listed below:

• Symmetric Key encryption
• Public Key encryption

Question 16.
What is a certificate?
Answer:
A certificate is a package of information that identifies a user and a server. It contains information such as an organization’s name, the organization that issued the certificate, the users’ email address and country, and the user’s public key.

Question 17.
What is a digital certificate?
Answer:

• A digital certificate in a client-server model of communication.
• It is one of the examples of Asymmetric Encryption.

Question 18.
What is a digital signature?
Answer:
Digital signatures are based on asymmetric cryptography and can provide assurances of evidence to origin, identity, and status of an electronic document, transaction, or message, as well as acknowledging informed by the signer.

Question 19.
Write a note on Cyberlaw or Internet law.
Answer:
Cyberlaw or Internet law is a term that encapsulates the legal issues related to using the Internet.

Question 20.
Write about IT Act 2000.
Answer:
IT Act 2000 is an act to provide legal recognition for transactions carried out by means of Electronic Data Interchange (EDI) and other means of electronic communication.

Part III

Short Answers 3 Marks

Question 1.
What are the guidelines of ethics?
Answer:
GUIDELINES OF ETHICS:
Generally, the following guidelines should be observed by computer users:

• Honesty: Users should be truthful while using the internet.
• Confidentiality: Users should not share any important information with unauthorized people.
• Respect: Each user should respect the privacy of other users.
• Professionalism: Each user should maintain professional conduct.
• Obey The Law: Users should strictly obey the cyber law in computer usage.
• Responsibility: Each user should take ownership and responsibility for their actions

Question 2.
Write a short note on ethics.
Answer:
Ethics means “What is Wrong and What is Right”. It is a set of moral principles that rule the behavior of individuals who use computers. An individual gains knowledge to follow the right behavior, using morals that are also known as ethics. Morals refer to the generally accepted standards of right and wrong in society. Similarly, in the cyber world, there are certain standards such as

1. Do not use pirated software.
2. Do not use unauthorized user accounts.
3. Do not steal others’ passwords.
4. Do not hack.

Question 3.
Write a note on unauthorized access.
Answer:
UNAUTHORIZED ACCESS:
Unauthorized access is when someone gains access to a website, program, server, service, or another system by breaking into a legitimate user account.

For example, if someone tries guessing a password or user name for an account that was not theirs until they gained access, it is considered unauthorized access.

Question 4.
What are cyber-attack and cybersecurity?
Answer:

• Cyber attacks are launched primarily for causing significant damage to a computer system or for stealing important information from an individual or from an organization.
• Cybersecurity is a collection of various technologies, processes, and measures that reduces the risk of cyber-attacks and protects organizations and individuals from computer-based threats.

Question 5.
What is phishing? Explain with a suitable diagram.
Answer:
Phishing:
Phishing is a type of computer crime used to attack, steal user data, including login name, password and credit card numbers. It occurs when an attacker targets a victim into opening an e-mailer an instant text message.

The attacker uses phishing to distribute malicious links or attachments that can perform a variety of functions including the extraction of sensitive login credentials from victims.

Diagrammatic representation of Phishing

Question 6.
What is Pharming? Explain with suitable diagram.
Answer:
Pharming:
Pharming is a scamming practice in which malicious code is installed on a personal computer or server, misdirecting users to fraudulent web sites without their knowledge or permission.

Pharming has been called “phishing without a trap”. It is another way hackers attempt to manipulate users on the Internet. It is a cyberattack intended to redirect a website’s traffic to a fake site.

Diagrammatic representation of Pharming :

Question 7.
What do you mean by Man In The Middle attack or Janus attack? Illustrate in a diagram.
Answer:
Man In The Middle (MITM) :
A man-in-the-middle attack (MITM; also Janus attack) is an attack where the attacker secretly relays and possibly alters the communication between two parties who believe they are directly communicating with each other.

Example:
Suppose Alice wishes to communicate with Bob. Meanwhile, Mallory wishes to intercept the conversation to overhear and optionally to deliver a false message to Bob.

An illustration of the man-in-the-middle attack :

Question 5.
Write down the points to be noted to be safe from cybercrime.
Answer:
To protect the information the following points to be noted:

1. A complex password setting can make your surfing secured.
2. When the internet is not in use, disconnect it.
3. Do NOT open spam mail or emails that have an unfamiliar sender.
4. When using anti-virus software, keep it up to date.

Question 9.
Explain the working of the Proxy Server.
Answer:
A proxy server acts as an intermediary between the end-users and a web server. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resources available from a different server.

The proxy server examines the request, checks authenticity, and grants the request based on that. Proxy servers typically keep the frequently visited site addresses in their cache which leads to improved response time.

Question 10.
How to prevent cybercrime?
Answer:
To protect the information the following points to be noted:

• A complex password setting can make your surfing secured.
• When the internet is not in use, disconnect it.
• Do NOT open spam mail or emails that have an unfamiliar sender.
• When using anti-virus software, keep it up-to-date.

Part IV

Explain in Detail

Question 1.
List the computer crimes and their functions.
Answer:

Question 2.
Explain Hacking in detail.
Answer:
HACKING:
Hacking is intruding into a computer system to steal personal data without the owner’s permission or knowledge (like to steal a password). It is also gaining unauthorized access to a computer system, and altering its contents. It may be done in pursuit of criminal activity or it may be a hobby.
Diagrammatic representation of Hacking

Question 3.
Write short notes on:

1. Spam
2. Fraud
3. Cyberstalking
4. Spoofing
5. Virus
6. Worms

Answer:

1. Spam: Distribute unwanted email to a large number of internet users.
2. Fraud: Manipulating data, for example changing the banking records to transfer money to an unauthorized account.
3. Cyberstalking: Harassing through online.
4. Spoofing: It is a malicious practice in which communication is sent from an unknown source disguised as a source known to the receiver.
5. Virus: A virus is a small piece of computer code that can repeat itself and spreads from one computer to another by attaching itself to another computer file. One of the most common viruses is Trojan.
6. Worms: Worms are self – repeating and do not require a computer program to attach themselves. Worms continually look for vulnerabilities and report back to the author of the worm when weaknesses are discovered.

Question 4.
Explain the working of the Firewall server. Firewall Server:
Answer:
A firewall is a computer network security-based system that monitors and controls the incoming and outgoing network traffic based on predefined security rules. A firewall commonly establishes a block between a trusted internal computer network and entrusted computer outside the network.

They are generally categorized as network-based or host-based.

Network-based firewalls are positioned on the gateway computers of LANs [local area Network], WANs [Wide Area Network], and intranets.

Host-based firewalls are positioned on the network node itself. The host-based firewall may be a service as a part of the operating system or an agent application such as endpoint security or protection.

Question 5.
Explain public key encryption.
Answer:
PUBLIC KEY ENCRYPTION:
Public key encryption is also called asymmetric encryption. It uses the concept of a key-value pair, a different key is used for the encryption and decryption process. One of the keys is typically known as the private key and the other is known as the public key.

The private key is kept secret by the owner and the public key is either shared amongst authorized re.dQle.ats. cvr made, available to the public at large.

The data encrypted with the recipient’s public key can only be decrypted with the corresponding private key.

Question 6.
What is a digital signature? Explain the function of the digital signature with a suitable diagram.
Answer:
Digital Signature:
Digital signatures are based on asymmetric cryptography and can provide assurances of evidence to origin, identity, and status of an electronic document, transaction, or message, as well as acknowledging informed by the signer.

To create a digital signature, signing software (email) creates a one-way hash of the electronic data to be signed. The user’s private key encrypts the hash, returning a value that is unique to the hashed data.

The encrypted hash, along with other information such as the hashing algorithm, forms the digital signature. Any change in the data, even to a single bit, results in a different hash value. This attribute enables others to validate the integrity of the data by using the signer’s public key to decrypt the hash.

If the decrypted hash matches a second computed hash of the same data, it proves that the data hasn’t changed since it was signed.

If the two hashes don’t match, the data has either been tampered with in some way (indicating a failure of integrity) or the signature was created with a private key that doesn’t correspond to the public key presented by the signer (indicating a failure of authentication).

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Computer Science Guide Pdf Chapter 18 Tamil Computing Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Computer Science Solutions Chapter 18 Tamil Computing

11th Computer Science Guide Tamil Computing Text Book Questions and Answers

Very Short Answers

Question 1.
List of the search engines supporting Tamil.
Answer:
Google and Bing provide searching facilities in Tamil, which means you can search everything through Tamil. A Google search engine gives you an inbuilt Tamil virtual keyboard.

Question 2.
What are the keyboard layouts used in Android?
Answer:
Sellinam and Ponmadal are familiar Tamil keyboard layouts that work on the Android operating system in Smart phone using phonetics.

Question 3.
Write a short note about Tamil Programming Language.
Answer:
Based on the Python programming language, the first Tamil programming language “Ezhil” (எழில்) is designed. With the help of this programming language, you can write simple programs in Tamil.

Question 4.
What TSCII?
Answer:
TSCII (Tamil Script Code for Information Interchange) is the first coding system to handle our Tamil language in an analysis of an encoding scheme that is easily handled in electronic devices, including non-English computers.
This encoding scheme was registered in the IANA (Internet Assigned Numbers Authority) unit of ICANN.

Question 5.
Write a short note on Tamil Virtual Academy
Answer:
With the objectives of spreading Tamil to the entire world through the internet, Tamil Virtual University was established on 17th February 2001 by the Govt, of Tamil Nadu. Now, this organisation is functioning with the name “Tamil Virtual Academy”. This organisation offers different courses regarding the Tamil language, culture, heritage, etc., from kindergarten to under graduation level.

11th Computer Science Guide Tamil Computing Additional Questions and Answers

Part I

I. Choose The Correct Answer 1 Mark 

Question 1.
Human civilization developed with the innovation of computer in the ……………
(a) 11th century
(b) 13th century
(c) 16th century
(d) 20th century
Answer:
(d) 20th century

Question 2.
_______ internet users consider local language digital content to be more reliable than English.
a) 74%
b) 68%
c) 42%
d) 28%
Answer:
b) 68%

Question 3.
Getting government services through the internet is known as ……………
(a) e-library
(b) e-governance
(c) Tamil programming language
(d) Tamil translation applications
Answer:
(b) e-governance

Question 4.
From 2021 onwards, _______of people in India will access the internet using Tamil.
a) 74%
b) 68%
c) 42%
d) 28%
Answer:
a) 74%

Question 5.
The _______are used to search any information from cyberspace.
a) Search Engines
b) Browsers
c) Cookies
d) None of these
Answer:
a) Search Engines

Question 6.
In the top ten search engines, _______takes first place.
a) Google
b) Bing
c) Yahoo
d) None of these
Answer:
a) Google

Question 7.
In the top ten search engines,_______takes second place.
a) Google
b) Bing
c) Yahoo
d) None of these
Answer:
b) Bing

Question 8.
In the top ten search engines, _______takes third place.
a) Google
b) Bing
c) Yahoo
d) None of these
Answer:
c) Yahoo

Question 9.
_______search engine provides searching facilities in Tamil.
a) Google
b) Bing
c) Yahoo
d) Google and Bing
Answer:
d) Google and Bing

Question 10.
A _______search engine gives you an inbuilt Tamil virtual keyboard.
a) Google
b) Bing
c) Yahoo
d) Google and Bing
Answer:
a) Google

Question 11.
Getting Government services through the internet is known as_______
a) e-Services
b) e-Governance
c) Web Governance
d) None of these
Answer:
b) e-Governance

Question 12.
Outside India, the Government of _______provides all their services through the official website in Tamil.
a) Srilanka
b) Canada
c) Nepal
d) None of these
Answer:
a) Srilanka

Question 13.
_______are portal or website of collection of e-books.
a) E-Libraries
b) E-Learning
c) E-Content
d) None of these
Answer:
a) E-Libraries

Question 14.
_______ is a familiar Tamil keyboard interface software that is used for Tamil typing which works on Tamil Unicode, using phonetics.
a) NHM Writer
b) E-Kalappai
c) Lippikar
d) All the above
Answer:
d) All the above

Question 15.
_______is a familiar Tamil keyboard layout that works on the Android operating system in Smartphone using phonetics.
a) Sellinam
b) Ponmadal
c) Sellinam and Ponmadal
d) None of these
Answer:
c) Sellinam and Ponmadal

Question 16.
_______ office automation software provides a complete Tamil interface facility.
a) Microsoft Office
b) Open Office
c) Both A and B
d) None of these
Answer:
c) Both A and B

Question 17.
_______is office automation software working exclusively for Tamil.
a) Azhagi Unicode Editor
b) Ponmozhi & Menthamiz
c) Kamban and Vani
d) All the above
Answer:
d) All the above

Question 18.
_______ is a Tamil translation application having more than 30000 Tamil words equivalent to English words.
a) Thamizpori
b) Sellinam
c) Ponmadal
d) None of these
Answer:
a) Thamizpori

Question 19.
The first Tamil programming language is _______
a) Thamizpori
b) Ezhil
c) Kamban
d) None of these
Answer:
b) Ezhil

Question 20.
With the help of _______ programming language, you can write simple programs in Tamil.
a) Thamizpori
b) Ezhil
c) Kamban
d) None of these
Answer:
b) Ezhil

Question 21.
Expand TSCII
a) Telugu Script Code for Information Interchange
b) Total Script Code for Information Interchange
c) Tamil Script Code for Information Interchange
d) Technical Script Code for Information Interchange
Answer:
c) Tamil Script Code for Information Interchange

Question 22.
Computers are handle data and information as a _______ system.
a) Binary
b) Decimal
c) Octal
d) Hexadecimal
Answer:
a) Binary

Question 23.
The ASCII encoding system is applicable only for handling _______ language.
a) English
b) Hindi
c) French
d) Tamil
Answer:
a) English

Question 24.
_______is the first coding System to handle our Tamil language in an analysis of an encoding scheme that is easily handled in electronic devices, including non-English computers.
a) ASCII
b) TSCII
c) EBCDIC
d) None of these
Answer:
b) TSCII

Question 25.
IANA means _______
a) Internet Assigned Numbers Authority
b) Internet Assigned Names Authority
c) Internet Access Numbers Authority
d) Intranet Assigned Numbers Authority
Answer:
a) Internet Assigned Numbers Authority

Question 26.
Expand ISCII
a) International Script Code for Information Interchange
b) Internet Script Code for Information Interchange
c) Indian Script Code for Information Interchange
d) Instant Script Code for Information Interchange
Answer:
c) Indian Script Code for Information Interchange

Question 27.
_______encoding schemes specially designed for Indian languages including Tamil.
a) ASCII
b) EBCDIC
c) BCD
d) ISCII
Answer:
d) ISCI

Question 28.
_______ is an encoding system, designed to handle various world languages, including Tamil.
a) ASCII
b) EBCDIC
c) UNICODE
d) ISCII
Answer:
c) UNICODE

Question 29.
Unicode first version 1.0.0 was introduced on _______
a) October 1991
b) October 2001
c) October 1993
d) October 1999
Answer:
a) October 1991

Question 30.
A(n) _______is needed to access electronic systems such as computer and smartphone.
a) Browser
b) Operating system
c) Search Engine
d) None of these
Answer:
b) Operating system

Question 31.
Identify the correct statement from the following.
a) An operating system should be easy to work and its environment should be in an understandable form.
b) Windows Tamil Environment interface shows all windows elements such as Taskbar, desktop elements, names of icons, commands in Tamil.
c) Among the various encoding scheme, Unicode is suitable to handle Tamil.
d) All the above
Answer:
d) All the above

Question 32.
Tamil Virtual University was established on _____ by the Govt, of Tamilnadu.
a) 17th February 1991
b) 17th February 2011
c) 17th February 2001
d) 27th February 2001
Answer:
c) 17th February 2001

Question 33.
_______organisation offers different courses regarding Tamil language, Culture, heritage, etc., from kindergarten to under graduation level.
a) Tamil Virtual Institute
b) Tamil Virtual Academy
c) Tamil Virtual Association
d) Tamil Virtual Organisation
Answer:
b) Tamil Virtual Academy

Question 34.
_______ is an open and voluntary initiative to collect and publish free electronic editions of ancient Tamil literary classics.
a) Project Madurai
b) Project Tamilnadu
c) Project Madras
d) Project Nellai
Answer:
a) Project Madurai

Question 35.
In 1998, Project Madurai released in Tamil script form as per _______ encoding.
a) ASCII
b) TSCII
c) BCD
d) None of these
Answer:
b) TSCII

Very Short Answers (2 Marks)

Question 1.
What is e-governance?
Answer:
Getting Government services through the internet is known as e-Governance. Govt, of Tamil Nadu, has been giving its services through the Internet. One can communicate with Govt, of Tamil Nadu from any comer of the state. One can get important announcements, government orders, and government welfare schemes from the web portal of Govt. of. Tamil Nadu.

Question 2.
Which search engine provides an inbuilt Tamil virtual keyboard.
Answer:
The Google search engine gives you an inbuilt Tamil virtual keyboard.

Question 3.
Explain Tamil translation applications.
Answer:
Thamizpori (தமிஸ்ப்பூரி) is a Tamil translation application having more than 30000 Tamil words equivalent to English words. Using this application, we can translate small English sentences into Tamil. Google also gives an online translation facility, using this online facility we can translate from Tamil to any other language and vice versa.

Question 4.
Write about the Tamil translation application.
Answer:
Thamizpori (தமிஸ்ப்பூரி) is a Tamil translation application having more than 30000 Tamil words equivalent to English words? Using this application, we can translate small English sentences into Tamil. Google also gives an online translation facility, using this online facility we can translate from Tamil to any other language vice versa.

Question 5.
Explain ISCII.
Answer:
Indian Script Code for Information Interchange (ISCII ), is one of the encoding schemes specially designed for Indian languages including Tamil. It was unified with Unicode.

Short Answers

Question 1.
What is Unicode?
Answer:
Unicode is an encoding system, designed to handle various world languages, including Tamil. Its first version 1.0.0 was introduced in October 1991. While the introduction of this scheme can be able to handle nearly 23 languages including Tamil. Among the various encoding scheme, Unicode is suitable to handle Tamil.

Question 2.
List the website address of popular e-Libraries.
Answer:

Question 3.
Write a short note on Tamil on the internet.
Answer:
Internet is the best information technological device, through which we get know everything from the Internet. In 2017 a study conducted by KPMG a Singapore-based organization along with google reported that Tamil topped the list, among the most widely used languages in India where 42% are using the Internet in Tamil. Moreover, in 2021 onwards, 74% of people in India will access the internet using Tamil and it will be in the top usage of the Internet in India.

Question 4.
Write a note on Unicode.
Answer:
Unicode is an encoding system, designed to handle various world languages, including Tamil. Its first version 1.0.0 was introduced in October 1991. While the introduction of this scheme can be able to handle nearly 23 languages including Tamil. Among the various encoding scheme, Unicode is suitable to handle Tamil.

Question 5.
Write a note on the Tamil operating system.
Answer:
An operating system should be easy to work and its environment should be in an understandable form. Thus, all operating systems used in computers and smartphones offered an environment in Tamil.
Windows Tamil Environment interface should be downloading and install from the internet. It shows all windows elements such as Taskbar, desktop elements, names of icons, commands in Tamil.

Explain in Detail (5 Marks)

Question 1.
Write about Tamil Office Automation Applications.
Answer:
Famous Office automation software like Microsoft Office, Open Office, etc., provides a complete Tamil interface facility. These softwares are downloadable and installed on your computer.

After installation, our office automation software environment will completely change to Tamil. Menu bars, names of icons, dialog boxes will be shown in Tamil. Moreover, you can save files with Tamil names and create folders with Tamil names.

Apart from that Tamil Libra Office, Tamil Open Office, Azhagi Unicode Editor, Ponmozhi, Menthamiz, Kamban, Vani are office automation software working exclusively for Tamil. These applications are designed to work completely in Tamil.

Tamilnadu State Board New Syllabus Samacheer Kalvi 11th Computer Science Guide Pdf Chapter 2 Number Systems Text Book Back Questions and Answers, Notes.

Tamilnadu Samacheer Kalvi 11th Computer Science Solutions Chapter 2 Number Systems

11th Computer Science Guide Number Systems Text Book Questions and Answers

Part – I

I. Choose The Correct Answer :

Question 1.
Which is a basic electronic circuit which operates on one or more signals?
a) Boolean algebra
b) Gate
c) Fundamental gates
d) Derived gates
Answer:
b) Gate

Question 2.
Which gate is called as the logical inverter?
a) AND
b) OR
c) NOT
d) XNOR
Answer:
c) NOT

Question 3.
A + A = ?
a) A
b) O
c) 1
d) A
Answer:
a) A

Question 4.
NOR is a combination of ?
a) NOT(OR)
b) NOT(AND)
c) NOT(NOT)
d) NOT(NOR)
Answer:
a) NOT(OR)

Question 5.
NAND is called as _______ Gate
a) Fundamental Gate
b) Derived Gate
c) Logical Gate
d) Electronic gate
Answer:
b) Derived Gate

Part II

Short Answers:

Question 1.
What is Boolean Algebra?
Answer:
Boolean algebra is a mathematical discipline that is used for designing digital circuits in a digital computer. It describes the relationship between inputs and outputs of a digital circuit.

Question 2.
Write a short note on NAND Gate.
Answer:
The NAND gate operates an AND gate followed by a NOT gate. It acts in the manner of the logical operation “AND” followed by an inversion. The output is “false” if both inputs are “true” otherwise, the output is “true”. In other words, the output of the NAND gate is 0 if and only if both the inputs are 1, otherwise the output is 1.
The logical symbol of the NAND gate is

The truth table for NAND gate is

Question 3.
Draw the truth table for the XOR gate.
Answer:
The truth table for XOR gate is

Question 4.
Write the associative laws?
Answer:
A + (B + C) = (A + B) + C
A.(B.C) = (A.B).C

Question 5.
What are derived gates?
Answer:
The logic gates which are derived from the fundamental gates are called derived gates. Ex. NAND, NOR, XOR and XNOR are derived gates.

Part – III

Explain In Brief

Question 1.
Write the truth table of fundamental gates.
Answer:
The fundamental logic gates are AND, OR, and NOT gates.
The truth table for AND Gate is

The truth table for OR gate is

The truth table for NOT gate is

Question 2.
Write a short note on the XNOR gate.
Answer:
The XNOR (exclusive – NOR) gate is a combination XOR gate followed by an inverter. Its output is “true” if the inputs are the same, and “false” if the inputs are different. In simple words, the output is 1 if the input is the same, otherwise, the output is 0. The logic symbol of the XNOR gate is

The truth table for XNOR Gate is

Question 3.
Reason out why the NAND and NOR are called universal gates?
Answer:
NAND and NOR gates are called Universal gates because the fundamental logic gates can be realized through them.

Question 4.
Give the truth table of XOR gate.
Answer:
The truth table for XOR Gate is

Question 5.
Write the De Morgan’s law.
Answer:
De Morgan’s \(\overline{\mathrm{A}+\mathrm{B}}\) = \(\overline{\mathrm{A}}\) . \(\overline{\mathrm{B}}\)
(\(\overline{\mathrm{A}+\mathrm{B}}\)) = \(\overline{\mathrm{A}}\) + \(\overline{\mathrm{B}}\)

Part IV

Explain In Detail

Question 1.
Explain the fundamental gates with an expression and truth table.
Answer:
A gate is a basic electronic circuit which operates on one or more signals to produce an output signal. There are three fundamental gates namely AND, OR and NOT.

AND Gate
The AND gate can have two or more input signals and produce an output signal. The output is “true” only when both inputs are “true” otherwise, the output is “false”. In other words the output will be 1 if and only if both inputs are 1; otherwise, the output is 0.

The logical symbol of the AND gate is

The output of the AND gate is C = A . B or C = AB
The truth table for AND Gate is

OR Gate
The OR gate gets its name from its behaviour like the logical inclusive “OR”. The output is “true” if either or both of the inputs are “true”. If both inputs are “false” then the output is “false”. In other words, the output will be 1 if and only if one or both inputs are 1; otherwise, the output is 0.
The logical symbol of the OR gate is

The OR gate output is C = A OR B. We use the + sign to denote the OR function. Therefore, C = A + B.
The truth table for OR Gate is

NOT Gate
The NOT gate, called a logical inverter, has only one input. It reverses the logical state. In other words the output C is always the complement of the input.
The logical symbol of the NOT gate is

The boolean function of NOT gate is C = NOT A. In boolean algebra, the overbar stands for NOT operation. Therefore, \(C=\bar{A}\)
The truth table for NOT gate is