CBSE Class 10 Science Chapter-4 Carbon and Its Compounds Important Questions – Free PDF Download
Free PDF download of Important Questions with Answers for CBSE Class 10 Science Chapter 4 – Carbon and Its Compounds prepared by expert Science teachers from latest edition of CBSE(NCERT) books only by CoolGyan to score more marks in CBSE board examination.
CBSE Class 10 Science Carbon and Its Compounds Chapter-4 Important Questions
CBSE Class 10 science Important Questions Chapter 4 – Carbon and Its Compounds
3 Mark Questions
1. Complete the following reaction
(i) 
(ii) 
(iii) 
Ans. (i) 
(ii) 
(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
4. Draw the structures of the following compounds
(a) Ethanoic acid
(b) Bromopentane
(c) Butanone
Ans. (a) 
Ethanoic acid
(b) 
Bromopentane
(c) 
Butanone
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)
13. Write three difference between ethanol and ethanoic acid on the basis of chemical properties?
Ans. (i) On adding a small amount of 
to ethanoic acid 
gas is evolved with brisk effervescence and no such reaction takes place in case of ethanol
(ii) Ethanol is neutral so does not bring any change in the colour of litmus paper but ethanoic acid is acidic and changes the colour of a blue litmus strip to red when dipped in it.
(iii) Ethanoic acid reacts with NaOH and KOH to form salt and water whereas ethanol fails to react.
14. Given a chemical test to distinguish between
(i) Ethane and ethane
(ii) Ethanol and ethanoic acid
(iii) Soaps and Detergents
Ans. (i) Ethane decolorizes the yellow colour of bromine while ethane does not.
(ii) Ethanoic acid gives a brisk effervescence with sodium hydrogen carbonate while ethanol does not.
(iii) Soaps form curdy white precipitate or scum with hard water while detergents do not form any precipitate.
15. Name the functional groups present in the following compounds?
(i) 
(ii)
(iii) 
Ans. (i) 
(ii) 
(iii) 
16. What are esters? Write an equation to show the formation of ester?
Ans. Esters are pleasant smelling compounds and are commonly used as flavoring agents. Monocarboxylic acids react with alcohol to form esters and water. This reaction is called as esterification
17. What will be the formula and electron dot structure for cyclopentane?
Ans. Formula of cyclopentane is
. The electron dot structure cyclopentane is:
18. How many structural isomers can you draw for pentane?
Ans. The isomers are as under:
19. What is a homologous series? Explain with an example.
Ans. Series of compounds in which the same functional group substitutes for hydrogen in a carbon chain is called homologues series. The difference between the formulae of any two successive members is 
and difference between the molecular formula is 14 u.
20. How can ethanol and Ethanoic acid be differentiated on the basis of their physical and chemical properties?
Ans. On the basis of physical properties: Melting and boiling points of ethanol is 156 K and 351 K but melting and boiling point of Ethanoic acid is 290 K and 391 K respectively.
On the chemical properties: Ethanoic acid reacts with sodium hydrogen carbonate liberating carbon dioxide while ethanol does not.
21. Why are carbon and its compounds used as fuels for most applications?
Ans. Carbon on combustion gives carbon dioxide and water. This reaction is accompanied by evolution of heat and light. The same is true for compounds of carbon. That is why carbon and its compounds are used as fuel for most applications.
22. Explain the formation of scum when hard water is treated with soap.
Ans. Hard water contains hydrogen carbonates, chlorides and sulphates of calcium and magnesium which reacts with soap to form scum. For example, calcium chloride reacts with soap to form scum.
Sodium stearate + Calcium chloride 
sodium chloride + Calcium stearate(scum)
23. What change will you observe if you test soap with litmus paper (red and blue)?
Ans. Soap is sodium or potassium salt of fatty acid. It is obtained by treating of oil with caustic soda. Sodium stearate is thus a salt of weak acid and strong base. Its water solution will be slightly alkaline and will turn red litmus red.
24. What is hydrogenation? What is its industrial application?
Ans. Unsaturated hydrocarbons add hydrogen in presence of catalysts such as palladium or nickel to give saturated hydrocarbons. This process is called hydrogenation.
It is commercially used for converting vegetable oils to ‘vanaspati’ ghee in presence of nickel as catalyst.
25. Explain in mechanism of the cleaning action of soap.
Ans. Soap are sodium or potassium salt of fatty acids. Two ends of molecules of soap behave differently. This ionic end is hydrophilic and it is oriented towards water. The other hydrocarbon end is hydrophobic and it is oriented towards dirt which is oily in nature. A micelle formation around the oily dirt takes place. When flushed with excess of water, the micelle containing the dirt is removed, thus cleaning the clothes, etc.
26. An organic compound X with a molecular formula C undergoes oxidation with in presence of alkaline 
to form a compound I X on heating in presence of Cone. 11 at 443 K gives Z. which on reaction with 112 cm presence of 11 gives back ‘X. ‘‘Z’ reacts with Br (aq) and decolorizes it. Identify X, Y, & Z and write the reactions involved.
Ans.
27. ‘A’ compound works well with hard water. It is used for making shampoos &products for cleaning clothes. A is not 100% biodegradable and causes water pollution. ‘B’ does not work well with hard water. It is 100% biodegradable and does not create water pollution. Identify A & B.
Ans. ‘Y’ will burn with a sooty flame. So it is an unsaturated hydrocarbon.
28. A cyclic compound ‘X’ has molecular formula 
. It is unsaturated and burns with sooty flame. Identify ‘X’ and write its structural formula. Will it decolonze bromine water or not and why?
Ans. 
It does not decolorize bromine water because it does not undergo addition reaction.
29. An organic compound ‘A’ is a constituent of antifreeze and has the molecular formula 
. upon reaction with alkaline the compound ‘A’ is oxidized to another ‘B’ with formula C Identify the compound A’ and ‘B’. Write the chemical equation for the reaction which leads to the formulation of ‘B’
Ans. 
30. Two compounds ‘X’ and ‘Y’ have the same formula C One of them reacts with sodium metal to liberate 112 and CO with NaHCO Second one does not reacts with Na metal and NaHCO but undergo hydrolysis with NaOH to form salt of carboxylic acid and compound ‘Z’ which is called wood spirit. Identify ‘X’, ‘Y’, and ‘Z’ and write chemical equation for the reaction involved.
Ans.
31. A compound ‘X’ with molecular formula C burns with a sooty flame. It decolourise bromine water. Identify ‘X’ Will it dissolve in water or not? Will it conduct electricity in aq. Solution? Will it have high melting point or low melting point?
Ans. ‘X’ is ethene. It will neither dissolve in water nor conduct electricity because it is a covalent compound. It has low melting point.
