NCERT Solutions for class 10 Science Chapter 4:Carbon and Its Compounds

NCERT Solutions for class 10 Science Chapter 4 Exercise Question

Question 1

Ethane, with the molecular formula C₂H₆ has

(a) 6 covalent bonds.

(b) 7 covalent bonds.

(c) 8 covalent bonds.

(d) 9 covalent bonds

Answer

b) 7 covalent bonds

Question 2

Butanone is a four-carbon compound with the functional group
(a) carboxylic acid
(b) aldehyde
(c) ketone
(d) alcohol

Answer

C) Ketone.

Question 3

While cooking, if the bottom of the vessel is getting blackened on the outside, it means that

(a) the food is not cooked completely.

(b) the fuel is not burning completely.

(c) the fuel is wet.

(d) the fuel is burning completely.

Answer

b)the fuel is not burning completely

Question 4

Explain the nature of the covalent bond using the bond formation in CH₃Cl

Answer

CH₃Cl is form by 1 carbom atom and 3 hydrogen and 1 chlorine Carbon has four valence electrons. It shares 1 electron with 3 hydrogen atoms and 1 electron with chlorine --- Chlorine has 7 electron in outer shell.It completes its outer shell by sharing one electron of carbon atom and 3 hydrogen atoms complete their shells by sharing three electrons of carbon atom. CH₃Cl completes its octet configuration.Hence the bonding that exists in CH₃Cl is a covalent bonding.

Question 5

Draw the electron dot structures for

(a) ethanoic acid

(b) H₂ S

(c) propanone

(d) F₂

Answer

a)

b)

c)

d)

Question 6

What is a homologous series? Explain with an example.

Answer

A series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called a homologous series.The general formula of this series is C_nH_2n+2

For example Methane CH₄ Ethane CH₃CH₃

Question 7

How can ethanol and ethanoic acid be differentiated on the basis of their physical and chemical properties?

Answer

Question 8

Why does micelle formation take place when soap is added to water? Will a micelle be formed in other solvents such as ethanol also?

Answer

Soap molecule has two ends. One end is hydrophilic and another end is hydrophobic. when soap is added to water Micelle formation takes place due the hydrocarbon chains of soap molecules are hydrophobic which are insoluble in water, but the ionic ends of soap molecules are hydrophilic that is, it interacts with water and hence soluble in water.Micelle is not formed in other solvent such as ethanol.

Question 9

Why are carbon and its compounds used as fuels for most applications?

Answer

Carbon and its compounds have large amount calorific values which give out a lot of energy.That why we used carbon and its compounds as fuels for most applications

Question 10

Explain the formation of scum when hard water is treated with soap?

Answer

Calcium and magnesium present in the hard water react with soap to from insoluble precipitate which is called as scrum.

Question 11

What change will you observe if you test soap with litmus paper (red and blue)?

Answer

soap is alkaline in nature so it turn Red litmus to blue.but in the soap solution, the blue litmus remains blue.

Question 12

What is hydrogenation? What is its industrial application?

Answer

Hydrogenation is an addition reaction between the hydrogen and other compounds in the presence of a catalyst to give saturated hydrocarbons. It is used to prepare vegetable ghee (or vanaspati ghee) from vegetable oils.

Question 13

Which of the following hydrocarbons undergo addition reactions: C₂H₆, C₃H₈, C₃H₆, C₂H₂ and CH₄.

Answer

Only unsaturated hydrocarbons undergo addition reactions. C₃H₆ and C₂H₂ are unsaturated hydrocarbons which undergo addition reactions.

Question 14

Give a test that can be used to differentiate between saturated and unsaturated hydrocarbons.

Answer

Bromine water test – is used to differentiate between the unsaturated compounds and the saturated compounds. So bromine is used in the form of bromine water. Bromine water has a red-brown color due to the presence of bromine in it. When bromine water is added to an unsaturated compound, then bromine gets added to the unsaturated compound and the red-brown color of bromine water is discharged. then it will be an unsaturated hydrocarbon but saturated hydrocarbon do not decolorize bromine water.

Question 15

Explain the mechanism of the cleaning action of soaps.

Answer

A soap molecule have of two parts: tail. It is hydrophobic in nature.
Head: It is hydrophilic in nature.
When soap added to dirty water then the hydrophobic part of soap get attach to dirt while the hydrophilic part remain on the surface of water.This formation is called a micelle. Soap in the form of a micelle is able to clean, since the oily dirt will be collected in the centre of the micelle. The micelles stay in solution as a colloid and will not come together to precipitat because of ion-ion repulsion. Thus, the dirt suspended in the micelles is also easily rinsed away