CBSE Class 10 Science Important Questions Chapter 4 Carbon and Its Compounds Part 3

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3 Marks Questions

1. Complete the following reaction

(i)

(ii)

(iii)

Ans. (i)

(ii)

Complete the following reaction

Complete the Following Reaction

Complete the following reaction

(iii)

2. What is the role of concentrated in the esterification reaction?

Ans. In esterification reaction a carboxylic acid reacts with alcohol to form ester and water in the presence of concentrated sulphuric acid. This reaction is reversible and this reverse reaction is called ester hydrolysis.

Concentrated sulphuric acid being a strong dehydrating agent removes water from the reaction mixture. As a result, the reaction proceeds only is the forward direction to form ester.

3. What will be the formula and electron dot structure of cyclopentane?

Ans. It is a cyclic compound with formula. The structure of the compound is represented as

Formula and electron dot structure of cyclopentane

Formula and Electron Dot Structure of Cyclopentane

Formula and electron dot structure of cyclopentane

4. Draw the structures of the following compounds

(a) Ethanoic acid

(b) Bromopentane

(c) Butanone

Ans.

(a)

Ethanoic acid

Ethanoic Acid

Ethanoic acid

(b) Bromopentane

(c)

Bromopentane

Bromopentane

Bromopentane

5. Give names of the following

(a) An aldehyde derived from ethane

(b) Ketone derived from butane

(c) Compound obtained by the oxidation of ethanol by chromic anhydride

Ans. (a) Ethanal

(b) Butanone

(c) Ethanal

6. What is meant by denatured alcohol?

What is the need to denature alcohol?

Ans. Ethyl alcohol which contains small amount of methyl alcohol or copper sulphate is called denatured alcohol. The purpose of denaturing of alcohol is to make it unfit for drinking purposes.

7. Write chemical equations of the reactions of ethanoic acid with

(a) Sodium

(b) Sodium carbonate

(c) Ethanol in the presence of conc.

Ans. (a)

(b)

(c)

8. Complete the reaction and names of the products formed

(i)

(ii)

(iii)

Ans. (i)

(ii)

(iii

9. What is a homologous series? State any two characteristics of homologous series?

Ans. A series of similarly constituted compounds in which the members present have the same functional group, same chemical properties and any two successive members is a particular series differ in their molecular formula by group.

(i) Same functional group

(ii) Same chemical properties.

10. Give the structural formulas for

(i) Methyl Ethanoate

(ii) Ethyl ethanoate Write two uses of Ester?

Ans. (i)

(ii)

Uses of esters:

(1) Esters have pleasant smell. These are used as flavouring agents and also in perfumes.

(2) Esters of glycerol know as triglycerides are used in the manufacture of soaps. This reaction is called saponification reaction.

11. What are enzymes? Name the enzymes required for the fermentation of sugar cane to ethanol?

Ans. Enzymes are the biocatalysts which catalyse the reactions in the living beings. In the process of fermentation of sugar into ethanol, two enzymes are used.

Sugar glucose fructose

Glucose and Fructose

12. The formula of an ester is .Write the formulae of the acid and alcohol from which the ester is prepared.

Ans. The molecular formula for acid is (Butanoic acid) and for alcohol is

(Ethyl alcohol)

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