NCERT Exemplar Chapter 4 Carbon and its Compounds Class 10 Science Solutions

NCERT Exemplar Class 10 Science Chapter 4 Carbon and its Compounds Solutions

NCERT Exemplar Solutions for Class 10 Science Chapter 4 Carbon and its Compounds covers all the important questions and answers as well as advanced level questions. It helps in learning about the organic and inorganic compounds, covalent bonds, types and their properties, features of organic compounds like their melting point, boiling point, solubility, electric conductivity and nature of their reactions and also chemical properties of organic compounds.

The NCERT Exemplar solutions for class 10 science is very important for board exams. NCERT Exemplar Solutions for Class 10 Science Chapter 4 Carbon and its Compounds is provided by our experts. They prepared the best solutions which help the students in understanding the solutions in an easy way. This chapters also covers the other topics like oxidation, combustion, addition reaction and substitution reaction, 

Chapter Name	Chapter 4 Carbon and its Compounds
Book Title	NCERT Exemplar for Class 10 Science
Related Study	NCERT Solutions for Class 10 Science Chapter 4 Carbon and its Compounds Revision Notes for Class 10 Science Chapter 4 Carbon and its Compounds MCQ for Class 10 Science Chapter 4 Carbon and its Compounds Important Questions for Class 10 Science Chapter 4 Carbon and its Compounds
Topics Covered	MCQ Short Answers Questions Long Answers Questions

NCERT Exemplar Solutions for Chapter 4 Carbon and its Compounds Class 10 Science

Multiple Choice Questions

1. Carbon exists in the atmosphere in the form of

(a) carbon monoxide only
(b) carbon monoxide in traces and carbon dioxide
(c) carbon dioxide only
(d) coal

Solution

(c) carbon dioxide only

2. Which of the following statements are usually correct for carbon compounds? These
(i) are good conductors of electricity
(ii) are poor conductors of electricity
(iii) have strong forces of attraction between their molecules
(iv) do not have strong forces of attraction between their molecules 

(a) (i) and (iii)
(b) (ii) and (iii)
(c) (i) and (iv)
(d) (ii) and (iv)

Solution

(d) (ii) and (iv) 

Carbon compounds form covalent bonds and hence they have very weak forces of attraction. This is the reason why carbon compounds are poor conductors of electricity.

3. A molecule of ammonia (NH₃) has

(a) only single bonds
(b) only double bonds
(c) only triple bonds
(d) two double bonds and one single bond

Solution

(a) only single bonds 

Nitrogen contains three valence electrons while hydrogen contains 1. Therefore, three hydrogen atoms combine with one nitrogen atom to form ammonia. The bonds formed are single bonds.

 

4. Buckminsterfullerene is an allotropic form of
(a) phosphorus
(b) sulphur
(c) carbon
(d) tin

Solution

(c) carbon

Diamond, Graphite, Lonsdaleite, C60 (Buckminsterfullerene or buckyball), C540, C70, Amorphous carbon, and h) single-walled carbon nanotube, or buckytube are the allotropes of carbon.

5. Which of the following are correct structural isomers of butane?

(a) (i) and (iii) 
(b) (ii) and (iv) 
(c) (i) and (ii) 
(d) (iii) and (iv) 

Solution

(c) (i) and (ii) 

Chemical formula of Butane is C₄H₁₀.
Here, option iii) and iv) have 8 hydrogen atoms, hence they are wrong.

6.

In the above given reaction, alkaline KMnO₄ acts as
(a) reducing agent
(b) oxidising agent
(c) catalyst
(d) dehydrating agent

Solution

(b) oxidising agent 

During oxidation of ethanol, two hydrogen atoms are replaced by one atom of oxygen. Potassium provides for the addition of oxygen.

7. Oils on treating with hydrogen in the presence of palladium or nickel catalyst form fats. This is an example of
(a) Addition reaction
(b) Substitution reaction
(c) Displacement reaction
(d) Oxidation reaction

Solution

(a) Addition reaction 

As hydrogen is added to oil, hence it is an addition reaction.

8. In which of the following compounds, — OH is the functional group?
(a) Butanone
(b) Butanol
(c) Butanoic acid
(d) Butanal

Solution

(b) Butanol 

Suffix ol in used for compound with OH functional group.

9. The soap molecule has a
(a) hydrophilic head and a hydrophobic tail
(b) hydrophobic head and a hydrophilic tail
(c) hydrophobic head and a hydrophobic tail
(d) hydrophilic head and a hydrophilic tail

Solution

(a) hydrophilic head and a hydrophobic tail

As oil and grease have a hydrophobic tail, they get trapped inside a micelle. Hydrophobic head makes the outer surface of micelle. Hence micelle is easily washed by water.

10. Which of the following is the correct representation of electron dot structure of nitrogen ?

Solution

(d)

Nitrogen atoms get 8 electrons in structure shown in option (d) whereas in other options it is different.

11. Structural formula of ethyne is

Solution

(a)

Chemical formula of Ethyne is C₂H₂.

12. Identify the unsaturated compounds from the following
(i) Propane
(ii) Propene
(iii) Propyne
(iv) Chloropropane 

(a) (i) and (ii)
(b) (ii) and (iv)
(c) (iii) and (iv)
(d) (ii) and (iii)

Solution

(d) (ii) and (iii)

Propene and propyne have double and triple bond respectively. Hence they are unsaturated compounds.

13. Chlorine reacts with saturated hydrocarbons at room temperature in the
(a) absence of sunlight
(b) presence of sunlight
(c) presence of water
(d) presence of hydrochloric acid

Solution

(b) presence of sunlight

Chlorine reacts with hydrocarbons in the presence of sunlight and displaces hydrogen atoms.

14. In the soap micelles
(a) the ionic end of soap is on the surface of the cluster while the carbon chain is in the interior of the cluster.
(b) ionic end of soap is in the interior of the cluster and the carbon chain is out of the cluster.
(c) both ionic end and carbon chain are in the interior of the cluster
(d) both ionic end and carbon chain are on the exterior of the cluster

Solution

(a) the ionic end of soap is on the surface of the cluster while the carbon chain is in the interior of the cluster. 

A micelle is a spherical aggregate soap molecules in soap solution. In the soap micelles the ionic end of soap is on the surface of the cluster while the carbon chain is in the interior of the cluster. 

15. Pentane has the molecular formula C₅H₁₂ . It has
(a) 5 covalent bonds
(b) 12 covalent bonds
(c) 16 covalent bonds
(d) 17 covalent bonds

Solution

(c) 16 covalent bonds

16. Structural formula of benzene is

Solution 

(c) 

Chemical formula of Benzene is C₆H₆.

17.  Ethanol reacts with sodium and forms two products. These are
(a) sodium ethanoate and hydrogen
(b) sodium ethanoate and oxygen
(c) sodium ethoxide and hydrogen
(d) sodium ethoxide and oxygen 

Solution

(c) sodium ethoxide and hydrogen 

2Na + 2CH₃CH₂OH → 2CH₃CH₂ONa + H₂

18. The correct structural formula of butanoic acid is

Solution

(d)

19. Vinegar is a solution of
(a) 50% – 60% acetic acid in alcohol
(b) 5% – 8% acetic acid in alcohol
(c) 5% – 8% acetic acid in water
(d) 50% – 60% acetic acid in water

Solution

(c) 5% – 8% acetic acid in water

20. Mineral acids are stronger acids than carboxylic acids because
(i) mineral acids are completely ionised
(ii) carboxylic acids are completely ionised
(iii) mineral acids are partially ionised
(iv) carboxylic acids are partially ionised

(a) (i) and (iv)
(b) (ii) and (iii)
(c) (i) and (ii)
(d) (iii) and (iv)

Solution

(a) (i) and (iv)

Mineral acids are stronger acids as they are completely ionized whereas carboxylic acids are weak acids as they are partially ionized.

21. Carbon forms four covalent bonds by sharing its four valence electrons with four univalent atoms, e.g. hydrogen. After the formation of four bonds, carbon attains the electronic configuration of
(a) helium
(b) neon
(c) argon
(d) krypton

Solution

(b) neon

After sharing four valence electrons with univalent atoms, the electronic configuration of carbon becomes 2, 8. This is the same as the electronic configuration of neon.

22. The correct electron dot structure of a water molecule is

Solution

(c) 

Option (c) represents complete octet configuration. Hence it is the right answer. 

23. Which of the following is not a straight chain hydrocarbon?

Solution

(d) 

24. Which among the following are unsaturated hydrocarbons ? 

(i) H₃C – CH₂ – CH₂ – CH₃
(ii) H₃C – C ≡ C – CH₃

(a) (i) and (iii) 
(b) (ii) and (iii) 
(c) (ii) and (iv) 
(d) (iii) and (iv) 

Solution

(c) (ii) and (iv) 

Unsaturated hydrocarbons have double or triple bonds..

25. Which of the following does not belong to the same homologous series?
(a) CH₄
(b) C₂H₆
(c) C₃H₈
(d) C₄H₈

Solution

(d) C₄H₈ 

General formula for C₄H₈ is C_nH_2n and other option it is C_nH_2n+2.

26. The name of the compound CH₃  — CH₂  — CHO is
(a) Propanal
(b) Propanone
(c) Ethanol
(d) Ethanal

Solution

(a) Propanal 

The compound has 3 carbon atoms and an aldehyde which add suffix -al to 3 carbon compound. 

27. The heteroatoms present in CH₃ —CH₂—O—CH₂—CH₂—Cl are

(i) oxygen
(ii) carbon
(iii) hydrogen
(iv) chlorine 

(a) (i) and (ii) 

(b) (ii) and (iii) 

(c) (iii) and (iv) 

(d) (i) and (iv)

Solution

(d) (i) and (iv) 

Oxygen and chlorine are heteroatoms as they are not among essential components of hydrocarbon.

28. Which of the following represents saponification reaction ?

(c) 2CH₃COOH + 2Na → 2CH₃ COONa + H₂
(d) CH₃COOC₂H₅ + NaOH → CH₃ COONa + C₂H₅OH

Solution

(d) CH₃COOC₂H₅ + NaOH → CH₃ COONa + C₂H₅OH

Saponification is a reaction in which ester on treatment with an alkali forms ethanol and sodium ethanoate.

29. The first member of alkyne homologous series is
(a) ethyne
(b) ethene
(c) propyne
(d) methane

Solution

(b) ethene 

Short Answer Questions 

30. Draw the electron dot structure of ethyne and also draw its structural formula 

Solution

Molecular formula = C₂H₂ 

Electron dot structure and Structural formula of ethyne.

31. Write the names of the following compounds

Solution

(a) Pentanoic acid 

(b) Butyne 

(c) Heptanal 

(d) Pentanol 

32. Identify and name the functional groups present in the following compounds. 

Solution

(a) Alcohol: -OH

(b) Carboxylic acid: 

(c)Ketone: 

(d)Alkene:

33. A compound X is formed by the reaction of a carboxylic acid C₂H₄O₂ and an alcohol in presence of a few drops of H₂SO₄. The alcohol on oxidation with alkaline KMnO₄ followed by acidification gives the same carboxylic acid as used in this reaction. Give the names and structures of

(a) carboxylic acid,
(b) alcohol and
(c) the compound X. Also write the reaction.

Solution

(a) Carboxylic acid is ethanoic acid.

(b) Alcohol is ethanol.

(c) X is ethyl ethanoate.

34. Why detergents are better cleansing agents than soaps ? Explain. 

Solution

Detergents work as cleansing agent both in hard and soft water. The charged ends of the detergents do not form insoluble precipitates with calcium and magnesium ions in hard water.

35. Name the functional groups present in the following compounds

(a) CH₃ CO CH₂ CH₂ CH₂ CH₃
(b) CH₃ CH₂ CH₂ COOH
(c) CH₃ CH₂ CH₂ CH₂ CHO
(d) CH₃ CH₂ OH

Solution

(a) Ketone
(b) Carboxylic acid
(c) Aldehyde
(d) Alcohol

36. How is ethene prepared from ethanol? Give the reaction involved in it.

Solution

Heating ethanol with excess of concentrated sulphuric acid at 443 K results in the dehydration of ethanol. The product formed is ethane.

37. Intake of small quantity of methanol can be lethal. Comment. 

Solution

In the liver, methanol is oxidised to methanal. Methanal reacts rapidly with the components of cells causing the protoplasm to coagulate. It also affects the optic nerve, causing blindness.

38. A gas is evolved when ethanol reacts with sodium. Name the gas evolved and also write the balanced chemical equation of the reaction involved.

Solution

When ethanol reacts with sodium it gives Sodium ethoxide and hydrogen gas is evolved.
2CH₃–CH₂–OH + 2Na → 2CH₃–CH₂–ONa⁺ + H₂

39. Ethene is formed when ethanol at 443 K is heated with excess of concentrated sulphuric acid. What is the role of sulphuric acid in this reaction ? Write the balanced chemical equation of this reaction.

Solution

Sulphuric acid acts as a catalyst and a dehydrating agent in the formation of ethene.

40. Carbon, Group (14) element in the Periodic Table, is known to form compounds with many elements. Write an example of a compound formed with
(a) chlorine (Group 17 of Periodic Table)
(b) oxgygen (Group 16 of Periodic Table)

Solution

(a) CCl₄- Carbon Tetra chloride

(b) Carbon – di – oxide – CO₂

41. In electron dot structure, the valence shell electrons are represented by crosses or dots.
(a) The atomic number of chlorine is 17. Write its electronic configuration
(b) Draw the electron dot structure of chlorine molecule

Solution

(a) KLM - 2, 8, 7

(b) Chlorine molecule is formed by formation of single covalent bond between two chlorine atoms. The electron dot structure of chlorine molecule is:

42. Catenation is the ability of an atom to form bonds with other atoms of the same element. It is exhibited by both carbon and silicon. Compare the ability of catenation of the two elements. Give reasons.

Solution

Because of the small size, carbon exhibits catenation much more than silicon or any other element. The small size makes the C–C bonds strong while the Si–Si bonds are comparatively weaker due to its large size.

43. Unsaturated hydrocarbons contain multiple bonds between the two C-atoms and show addition reactions. Give the test to distinguish ethane from ethene.

Solution

The two can be distinguished by subjecting them to the flame. Saturated hydrocarbons generally give a clear flame while unsaturated hydrocarbons give a yellow flame with lots of black smoke.

44. Match the reactions given in Column (A) with the names given in column (B). 

Answer

45. Write the structural formulae of all the isomers of hexane.

Solution

Hexane can exhibit five isomers with molecular formula C₆H₁₄.

46. What is the role of metal or reagents written on arrows in the given chemical reactions?

Solution

(a) Ni acts as a catalyst.

(b) Concentrated H2SO4acts as a catalyst.

(c) Alkaline KMnO4acts as an oxidising agent.

Long Answer Questions

47. A salt X is formed and a gas is evolved when ethanoic acid reacts with sodium hydrogen carbonate. Name the salt X and the gas evolved. Describe an activity and draw the diagram of the apparatus to prove that the evolved gas is the one which you have named. Also, write chemical equation of the reaction involved.

Solution

Ethanoic acid reacts with sodium hydrogen carbonate to produce sodium ethanoate and carbon dioxide gas. 

CH₃COOH + NaHCO₃ → CH₃COONa + H₂O + CO₂
Salt X is Sodium ethanoate and the gas evolved is carbon dioxide.

Activity 

• Set up the experiment as shown in figure.
• Take a spoon full of Sodium Hydrogen Carbonate in a test-tube and add 2ml of dilute ethanoic acid.
• Brisk effervescence occur in testtube.
• Pass the produce gas into lime water
• Lime water turn milky confirming the evolution of CO₂ .

48.  (a) What are hydrocarbons? Give examples.
(b) Give the structural differences between saturated and unsaturated hydrocarbons with two examples each.
(c) What is a functional group? Give examples of four different functional groups.

Solution

(a) Hydrocarbons are the compounds of carbon and hydrogen. Example: methane, ethane etc.

(b) Hydrocarbons containing carbon-carbon single bonds are known as saturated hydrocarbons whereas hydrocarbons containing atleast one carbon -carbon double or triple bond are known as unsaturated hydrocarbons.

(c) An atom/group of atoms joined in a specific manner which is responsible for the characteristic chemical properties of the organic compounds is known as a functional group.
Examples are hydroxyl group (–OH), aldehyde group (–CHO), carboxylic group (–COOH) etc.

49.  Name the reaction which is commonly used in the conversion of vegetable oils to fats. Explain the reaction involved in detail.

Solution

The reaction which is commonly used in the conversion of vegetable oils to fatsis known as hydrogenation.

50.  (a) Write the formula and draw electron dot structure of carbon tetrachloride.
(b) What is saponification? Write the reaction involved in this process.

Solution

(a) The formula for carbon tetrachloride is CCl₄ 

(b) The process of converting esters into salts of carboxylic acids and ethanol by treating them with a base is known as saponification.

CH₃COOC₂H₅ + NaOH → CH₃COONa + C₂H₅OH

51. Esters are sweet-smelling substances and are used in making perfumes. Suggest some activity and the reaction involved for the preparation of an ester with well labeled diagram.

Solution

Activity

• Take 1 mL ethanol (absolute alcohol) and 1 mL glacial acetic acid along with a few drops of concentrated sulphuric acid in a test tube.
• Warm the test tube ina water-bath at about 60°C for at least 15 minutes as shown in the Figure (It should not be heated directly on flame as the vapours of ethanol catch fire).
• Pour into a beaker containing 20-50 mL of water and smell the resulting mixture.
  
  

52.  A compound C (molecular formula, C₂H₄O₂ ) reacts with Na - metal to form a compound R and evolves a gas which burns with a pop sound. Compound C on treatment with an alcohol A in presence of an acid forms a sweet smelling compound S (molecular formula, C₃H₆O₂  ). On addition of NaOH to C, it also gives R and water. S on treatment with NaOH solution gives back R and A. Identify C, R, A, S and write down the reactions involved. 

Solution

• C —Ethanoic acid
• R —Sodium salt of ethanoic acid (sodium acetate) and gas evolved is hydrogen
• A —Methanol
• S —Ester (Methyl acetete)

(I) Compound C is Ethanoic acid [Acetic acid]
It reacts with sodium metal to form a compound called R. R is Sodium Ethanoate.
2CH₃COOH + 2Na → 2CH₃COONa + H₂
(II)
So compound S is Ester of Ethyl ethanoate and compound A is Ethanol
(III) CH₃COOC₂H₅ + NaOH → CH₃COONa + C₂H₅OH.
So, compound R is again Sodium Ethanoate.
So, compound C is Ethanoic acid

A is Ethanol
S is Ester R is sodium Ethanoate.

53. Look at Figure 4.1 and answer the following questions
(a) What change would you observe in the calcium hydroxide solution taken in tube B?
(b) Write the reaction involved in test tubes A and B respectively.
(c) If ethanol is given instead of ethanoic acid, would you expect the same change?
(d) How can a solution of lime water be prepared in the laboratory?

Solution

(a) Calcium hydroxide solution in test tube B turns milky.
(b) Reaction in Tube A
CH₃COOH + NaHCO₃ → CH₃COONa + CO₂ + H₂O
Reaction in tube B
Ca(OH)₂ + CO₂ → CaCO₃ + H₂O

(c) C₂H₅OH and Na₂CO₃ do not react, hence a similar change is not expected.
C₂H₅OH + Na₂CO₃ → No change

(d) By dissolving calcium oxide in water and decanting the supernatent liquid, lime water can be prepared.

54. How would you bring about the following conversions ? Name the process and write the reaction involved. 
(a) ethanol to ethene.
(b) propanol to propanoic acid. Write the reactions. 

Solution

(a) Dehydration of ethanol in the presence of concentrated H₂SO₄.

(b) (b) Oxidation of propanol using oxidising agent such as alkaline KMnO₄.

55. Draw the possible isomers of the compound with molecular formula C₃H₆O and also give their electron dot structures. 

Solution

The two possible isomers of the compound with molecular formula C₃H₆O are :

56. Explain the given reactions with the examples
(a) Hydrogenation reaction
(b) Oxidation reaction
(c) Substitution reaction
(d) Saponification reaction
(e) Combustion reaction

Solution

(a) In the presence of nickel catalyst, unsaturated hydrocarbons add hydrogen to give saturated hydrocarbons.

(b) On heating ethanol is oxidised to ethanoic acid in the presence of alkaline KMnO₄.

(c) Chlorine is added to hydrocarbonsin the presence of sunlight. 

(d) When Ester is treated with alkali, the reaction gives ethanol and Sodium ethanoate. This reaction is called saponification. 

Example : CH₃COOC₂H₅ + NaOH → CH₃COONa + C₂H₅OH
(e) Combustion is the burning of a substance in presence of Oxygen. 
Example: CH₄ + O₂ → CO₂ + H₂O + heat and light 

57.  An organic compound A on heating with concentrated H₂SO₄ forms a compound B which on addition of one mole of hydrogen in presence of Ni forms a compound C. One mole of compound C on combustion forms two moles of CO₂  and 3 moles of H₂O. Identify the compounds A, B and C and write the chemical equations of the reactions involved.

Solution

Compound C has the molecular formula C₂ H₆(Ethane) as it gives 2 moles of CO₂ and 3 moles of H₂O. The molecular formula of B should be C₂H₄(Ethene), as compound C is obtained by the addition of one mole of hydrogen to B. Compound A is alcohol as compound B is obtained by heating compound A with concentrated H₂SO₄. Therefore, compound A can be C₂H₅OH (Ethanol).

Compound A is Ethanol 
Compound A  = CH₃CH₂OH

2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O