Welcome to the NCERT Solutions for Class X Science Chapter 4, Carbon and its Compounds. This chapter explores the fascinating world of carbon compounds, including the properties and reactions of various organic compounds. The chapter discusses the different types of carbon compounds, including hydrocarbons, alcohols, carboxylic acids, and esters.
In this chapter, you will learn about the bonding and hybridization of carbon atoms, which are the basis for the formation of numerous organic compounds. You will also study the different types of chemical reactions, such as substitution, addition, and oxidation-reduction reactions, that carbon compounds can undergo.
The NCERT Solutions for Class X Science Chapter 4 provide detailed explanations and step-by-step solutions to all the questions in the textbook. With the help of these solutions, you can clear your doubts and understand the concepts thoroughly. So, let’s dive into the fascinating world of carbon compounds and learn about the role of carbon in the chemistry of life.

Download PDF of NCERT Solutions for Class 10 Science Chapter 4 Carbon and its Compounds

Answers of Science NCERT solutions for class 10 Chapter 4 Carbon and its Compounds

Chapter 4

Carbon & Its Compounds

Question 1:

What would be the electron dot structure of carbon dioxide which has the formula CO₂? 

Answer:

Electron dot structure of CO₂ is

Question 2:

What would be the electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur? (Hint − the eight atoms of sulphur are joined together in the form of a ring.)

Answer:

Electron dot structure of a sulphur molecule

Question 1:

How many structural isomers can you draw for pentane? 

Answer:

Three structural isomers are possible for pentane. 

(i)

(ii)

(iii)

Question 2:

What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?

Answer:

The two features of carbon that give rise to a large number of compounds are as follows:

1. Catenation − It is the ability to form bonds with other atoms of carbon.
2. Tetravalency − With the valency of four, carbon is capable of bonding with four other atoms.

Question 3:

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

Answer:

The formula for cyclopentane is C₅H₁₀. Its electron dot structure is given below.

Question 4:

Draw the structures for the following compounds.

(i) Ethanoic acid (ii) Bromopentane*

(iii) Butanone (iv) Hexanal

*Are structural isomers possible for bromopentane? 

Answer:

(i)

(ii) There are many structural isomers possible for bromopentane. Among them, the structures of three isomers are given.

(iii)

(iv)

Question 5:

Why do ionic compounds have high melting points? 

Answer:

Ionic compounds have strong electrostatic forces of attraction between the ions. Therefore, it requires a lot of energy to overcome these forces. That is why ionic compounds have high melting points.

Question 1:

Why is the conversion of ethanol to ethanoic acid an oxidation reaction? 

Answer:

Since the conversion of ethanol to ethanoic acid involves the addition of oxygen to ethanol, it is an oxidation reaction.

Question 2:

A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?

Answer:

When ethyne is burnt in air, it gives a sooty flame. This is due to incomplete combustion caused by limited supply of air. However, if ethyne is burnt with oxygen, it gives a clean flame with temperature 3000°C because of complete combustion. This oxy-acetylene flame is used for welding. It is not possible to attain such a high temperature without mixing oxygen. This is the reason why a mixture of ethyne and air is not used.

Question 1:

How would you distinguish experimentally between an alcohol and a carboxylic acid? Answer:

We can distinguish between an alcohol and a carboxylic acid on the basis of their reaction with carbonates and hydrogen carbonates. Acid reacts with carbonate and hydrogen carbonate to evolve CO₂ gas that turns lime water milky.

Alcohols, on the other hand, do not react with carbonates and hydrogen carbonates.

Question 2:

What are oxidising agents? 

Answer:

Some substances such as alkaline potassium permanganate and acidified potassium dichromate are capable of adding oxygen to others. These are known as oxidising agents.

Question 1:

Would you be able to check if water is hard by using a detergent? 

Answer:

Detergents are ammonium or sulphonate salts of long chain carboxylic acids. Unlike soap, they do not react with calcium and magnesium ions present in hard water to form scum. They give a good amount of lather irrespective of whether the water is hard or soft. This means that detergents can be used in both soft and hard water. Therefore, it cannot be used to check whether the water is hard or not.

Question 2:

People use a variety of methods to wash clothes. Usually after adding the soap, they ‘beat’ the clothes on a stone, or beat it with a paddle, scrub with a brush or the mixture is agitated in a washing machine. Why is agitation necessary to get clean clothes?

Answer:

A soap molecule has two parts namely hydrophobic and hydrophilic. With the help of these, it attaches to the grease or dirt particle and forms a cluster called micelle. These micelles remain suspended as a colloid. To remove these micelles (entrapping the dirt), it is necessary to agitate clothes.

Question 1:

Ethane, with the molecular formula C₂H₆ has

1. 6 covalent bonds.
2. 7 covalent bonds.
3. 8 covalent bonds.
4. 9 covalent bonds.

 Answer:

(b) Ethane has 7 covalent bonds.

Question 2:

Butanone is a four-carbon compound with the functional group

1. carboxylic acid.
2. aldehyde.
3. ketone.
4. alcohol.

Answer:

(c) The functional group of butanone is ketone.

Question 3:

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

1. the food is not cooked completely.
2. the fuel is not burning completely.
3. the fuel is wet.
4. the fuel is burning completely. 

Answer:

(b) While cooking, if the bottom of the vessel is getting blackened on the outside, then it means that the fuel is not burning completely.

Question 4:

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

Answer:

Carbon can neither lose four of its electrons nor gain four electrons as both the processes require extra amount of energy and would make the system unstable. Therefore, it completes its octet by sharing its four electrons with other carbon atoms or with atoms of other elements. The bonds that are formed by sharing electrons are  known as covalent bonds. In covalent bonding, both the atoms share the valence electrons, i.e., the shared electrons belong to the valence shells of both the atoms.

Here, carbon requires 4 electrons to complete its octet, while each hydrogen atom requires one electron to complete its duplet. Also, chlorine requires an electron to complete the octet. Therefore, all of these share the electrons and as a result, carbon forms 3 bonds with hydrogen and one with chlorine.

Question 5:

Draw the electron dot structures for

1. ethanoic acid.
2. H₂S.
3. propanone.
4. F₂. 

Answer:

1. Ethanoic acid
2. H₂S

3. Propanone
4. F₂

Question 6:

What is a homologous series? Explain with an example. 

Answer:

A homologous series is a series of carbon compounds that have different numbers of 

carbon atoms but contain the same functional group.

For example, methane, ethane, propane, butane, etc. are all part of the alkane homologous series. The general formula of this series is C_nH_2n+2.

Methane (CH₄)Ethane (CH₃CH₃)Propane (CH₃CH₂CH₃)Butane (CH₃CH₂CH₂CH₃)

It can be noticed that there is a difference of −CH₂ unit between each successive compound.

Question 7:

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

Answer:

• Ethanol is a liquid at room temperature with a pleasant odour while ethanoic acid has vinegar-like smell. The melting point of ethanoic acid is 17°C. This is below room temperature and hence, it freezes during winters.
• Ethanoic acid reacts with metal carbonates and metal hydrogen carbonates to form salt, water, and carbon dioxide gas while ethanol does not react with them.

For example,

For example,

Question 8:

In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?

Answer:

In the electrolytic refining of a metal M:

Anode → Impure metal M

Cathode → Thin strip of pure metal M 

Electrolyte → Solution of salt of the metal M 

Question 9:

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

Answer:

Most of the carbon compounds give a lot of heat and light when burnt in air. Saturated hydrocarbons burn with a clean flame and no smoke is produced. The carbon compounds, used as a fuel, have high calorific values. Therefore, carbon and its compounds are used as fuels for most applications.

Question 10:

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

Answer:

Soap does not work properly when the water is hard. A soap is a sodium or potassium salt of long chain fatty acids. Hard water contains salts of calcium and magnesium. When soap is added to hard water, calcium and magnesium ions present in water displace sodium or potassium ions from the soap molecules forming an insoluble substance called scum. A lot of soap is wasted in the process.

Question 11:

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

Since soap is basic in nature, it will turn red litmus blue. However, the colour of blue litmus will remain blue.

Question 12:

What is hydrogenation? What is its industrial application? 

Answer:

Hydrogenation is the process of addition of hydrogen. Unsaturated hydrocarbons are added with hydrogen in the presence of palladium and nickel catalysts to give saturated hydrocarbons.

This reaction is applied in the hydrogenation of vegetables oils, which contain long chains of unsaturated carbons.

Question 13:

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

Answer:

Unsaturated hydrocarbons undergo addition reactions. Being unsaturated hydrocarbons, C₃H₆ and C₂H₂ undergo addition reactions.

Question 14:

Give a test that can be used to differentiate chemically between butter and cooking oil. 

Answer:

Butter contains saturated fats. Therefore, it cannot be hydrogenated. On the other hand, oil has unsaturated fats. That is why it can be hydrogenated to saturated fats (solids).

Question 15:

Explain the mechanism of the cleaning action of soaps. 

Answer:

Cleansing action of soaps:

The dirt present on clothes is organic in nature and insoluble in water. Therefore, it cannot be removed by only washing with water. When soap is dissolved in water, its hydrophobic ends attach themselves to the dirt and remove it from the cloth. Then, the molecules of soap arrange themselves in micelle formation and trap the dirt at the  centre of the cluster. These micelles remain suspended in the water. Hence, the dust particles are easily rinsed away by water.

Access Answers of Science NCERT Class 10 Chapter 4 Carbon and Its Compounds

(All In text and Exercise Questions Solved)

In-text questions set 1 Page number 61

1. What would be the electron dot structure of carbon dioxide which has the formula CO₂?

Solution:

2. What would be the electron dot structure of a molecule of Sulphur which is made up of eight atoms of Sulphur? (Hint – The eight atoms of Sulphur are joined together in the form of a ring).

Solution:

In-text questions set 2 Page number 61

1. How many structural isomers can you draw for pentane?

Solution: Structural isomer of pentane are

n-pentane

2-methylbutane

2, 2-dimethylpropane

2-methylbutane

2. What are the two properties of carbon which lead to the huge number of carbon compounds we see around us?

Solution: Two properties of carbon which lead to the huge number of carbon compounds we see around us are

• Carbon has six valence electrons which are actually a high number of valency.
• Covalent bonding happens easily with carbon atoms and numerous others such as oxygen, chlorine, nitrogen, Sulphur, hydrogen, etc.

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

Solution:

4. Draw the structures for the following compounds.

(i) Ethanoic acid

(ii) Bromopentane*

(iii) Butanone

(iv) Hexanal

Solution: i)

ii)

iii)

iv)

5. How would you name the following compounds?

• CH₃—CH₂—Br
• 
• 

Solution:

1. Bromoethane
2. Methanal or Formaldehyde
3. 1 – Hexyne

In-text questions set 3 Page number 71

1. Why is the conversion of ethanol to ethanoic acid an oxidation reaction?

Solution:

Conversion of ethanol to ethanoic acid involves the removal of Hydrogen atom and addition of oxygen it is an oxidation reaction. In the first step, a H₂ molecule is removed from ethanol to form ethanal. As loss of Hydrogen is oxidation so, the reaction is an oxidation reaction. Similarly Oxygen atom is added to form ethanoic acid from ethanal. As, gain of Oxygen is called oxidation so, the reaction is an oxidation reaction.

2. A mixture of oxygen and ethyne is burnt for welding. Can you tell why a mixture of ethyne and air is not used?

Solution: A mixture of oxygen and ethyne is burnt for welding instead of mixture of ethyne and air because the production of heat is very important for welding metals. When oxygen and ethyne are burnt, it burns completely and produces a higher temperature than air and ethyne. Oxygen and ethyne produce very hot blue flame but the mixture of air and ethyne gives out a sooty flame which means that there are unburnt particles, resulting in lesser heat.

In text questions set 4 Page number 74

1. How would you distinguish experimentally between an alcohol and a carboxylic acid?

Solution: On reaction with Sodium Carbonate, Carboxylic acids produces carbon dioxide gas which turns lime water milky whereas alcohols do not give this reaction. This experiment can be used to distinguish an alcohol and carboxylic acid.

Reaction of Carboxylic acid with sodium carbonate:

2CH₃COOH + Na₂CO₃ → 2CH₃COONa + H₂O + CO₂

2. What are oxidising agents?

Solution: Oxidising agents are those compounds which either removes Hydrogen or adds oxygen to a compound. Ex: halogens, potassium nitrate, and nitric acid.

In text questions set 5 Page number 76

1. Would you be able to check if water is hard by using a detergent?

Solution: It is not possible to check if water is hard by using a detergent because detergents are salts of ammonium or sulphonates of long chain carboxylic acids. Unlike soaps they do not react with calcium and magnesium to distinguish nature of water.

2. People use a variety of methods to wash clothes. Usually after adding the soap, they ‘beat’ the clothes on a stone, or beat it with a paddle, scrub with a brush or the mixture is agitated in a washing machine. Why is agitation necessary to get clean clothes?

Solution: Agitation is necessary to get clean clothes as agitation aid soap micelles to trap the oil, grease or any other impurities that have to be removed. When they are being beaten or agitated, the particles are removed from the clothes’ surfaces and go into the water, thus cleaning the clothes.

Exercise questions Page number 77-78

1. Ethane, with the molecular formula C₂H₆ has

(a) 6 covalent bonds.

(b) 7 covalent bonds.

(c) 8 covalent bonds.

(d) 9 covalent bonds

Solution: Ethane, with the molecular formula C₂H₆ has 7 covalent bonds

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

Solution: Answer is option C i.e Ketone.

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.

Solution: Answer is option b. While cooking, if the bottom of the vessel is getting blackened on the outside indicates that the fuel is not burning completely.

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

Solution: Carbon can neither lose 4 electrons nor do gain four electrons as these process make the system unstable due to requirement of extra energy. Therefore CH₃Cl completes its octet configuration by sharing its 4 electrons with carbon atoms or with atoms of other elements. Hence the bonding that exists in CH₃Cl is a covalent bonding.

Here, carbon requires 4 electrons to complete its octet, while each hydrogen atom requires one electron to complete its duplet. Also, chlorine requires an electron to complete the octet. Therefore, all of these share the electrons and as a result, carbon forms 3 bonds with hydrogen and one with chlorine.

5. Draw the electron dot structures for

(a) ethanoic acid

(b) H₂ S

(c) propanone

(d) F₂

Solution:

a)

b)

c)

d)

6. What is a homologous series? Explain with an example.

A homologous series is a series of compounds, which has the same functional group. This also contains similar general formula and chemical properties. Since there is a change in the physical properties, we can say that there would be an increase in the molecular size and mass.

For example, methane, ethane, propane, butane, etc. are all part of the alkane homologous series. The general formula of this series is C_nH_2n+2. Methane CH₄ Ethane CH₃CH₃ Propane CH₃CH₂CH₃ Butane CH₃CH₂CH₂CH₃. It can be noticed that there is a difference of −CH2 unit between each successive compound.

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

Solution:

Ethanol	Ethanoic acid
Does not react with sodium hydrogen carbonate	Bubbles and fizzes with sodium hydrogen carbonate
A good smell	Smells like vinegar
No action in litmus paper	Blue litmus paper to red
Burning taste	Sour taste

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?

Solution: Micelle formation takes place because of the dirt particles in water and clean water. There are two mediums that are involved: one is pure water and the other being dirt (also called as impurities). The soap also has two mediums:

(i) organic tail and

(ii) ionic head

So the organic tail mixes and dissolves with the dirt whereas the oil or grease and ionic head dissolves and mixes with the water. Therefore, when the material to be cleaned is removed from the water, the dirt is taken off by the soap molecules in the water. Hence, the soap cleans by forming closed structures by the mutual repulsion of the micelles (positively charged heads).

Other solvents such as ethanol, in which sodium salt of fatty acids does not dissolve, so not able to form such micelles.

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

Solution: Carbon and its compounds used as fuels for most applications for they have high calorific values and give out a lot of energy. Most of the carbon compounds give a lot of heat and light when burnt in air.

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

Solution: Scrum is produced from reaction of hard water with soap. Calcium and magnesium present in the hard water form an insoluble precipitate that stick as a white which is also called as scrum.

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

Solution:When soap is dissolved in water, due to the formation of alkaline NaOH or KOH, the solution is alkaline. The solution changes the colour of the red litmus to blue, but in the soap solution, the blue litmus remains blue.

12. What is hydrogenation? What is its industrial application?

Solution: Hydrogenation is a process or a chemical reaction between hydrogen and other compounds. It is usually done in the presence of catalysts: for example nickel, palladium or platinum. Hydrogenation is used mainly to saturate organic compounds.

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

Solution: Unsaturated hydrocarbons undergo addition reactions. C₃H₆ and C₂H₂ are unsaturated hydrocarbons which undergo addition reactions.

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

Solution: Bromine water test – is used to differentiate between the unsaturated compounds (like alkenes and alkynes) and the saturated compounds. For this purpose, bromine is used in the form of bromine water. A solution of bromine in water is called 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. So, if an organic compound decolorizes bromine water, then it will be an unsaturated hydrocarbon (containing a double bond or a triple bond), but saturated hydrocarbon (alkanes) do not decolorize bromine water.

Bromine water test is perform to differentiate between the unsaturated compounds (like alkenes and alkynes) and the saturated compounds. Bromine water is added to an un-saturated hydrocarbon red brown color of bromine solution is discharged. So if there is dis-coloration then the compound will be an unsaturated Hydrocarbon.

15. Explain the mechanism of the cleaning action of soaps.

Solution: There are so many impurities and dirt mixed in water, and most of all the dirt does not dissolve in the water. Soap molecules are a combination of salts such as sodium or potassium. The molecules are of a long chain of carboxylic acids. So, when the carbon chain is dissolved in oil and the ionic end is dissolved in the water, the soap starts cleansing and trapping the dirt. When this happens, the soap molecules form structures that are called micelles are used for capturing the oil droplets and then the other end being the ionic faces. This will then form an emulsion in water and help in dissolving the dirt or impurities when the clothes are washed.

The soap molecules have different properties at different ends. The first end being the hydrophilic end which dissolves in the water and is attracted towards the water and the second one being the hydrophobic end is dissolved in the hydrocarbons and is repulsive to water. The hydrophobic tail aligns itself along the surface of the water because it is not soluble in the water.

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NCERT Solutions for Class 10 Science Chapter 4 Carbon and Its Compounds

Average Number of questions usually asked from this chapter is for two plus three marks. In the year 2017, a total of 15 marks questions were asked from this chapter whereas in the year 2018 the weightage was 2+3 = 5.

List of Section questions with type

Section number	Section name	Questions	Question type
Section 4.1	Bonding in Carbon – The covalent bond	2	2 short answers
Section 4.2	Versatile nature of carbon	5	2 very short answers, 3 long answers
Section 4.3	Chemical properties of Carbon compounds	2	2 long answer
Section 4.4	Some important carbon compounds – ethanol and ethanoic acid	2	1 short answer, 1 long answer
Section 4.5	Soaps and detergents	2	1 very short answer, 1 long answer

NCERT Solutions for Class 10 Science Chapter 4 Carbon and Its Compounds

Conclusion

NCERT Solutions for Class X Science Chapter 4, Carbon and its Compounds, is an essential chapter that provides a comprehensive understanding of the fascinating world of carbon compounds. The chapter discusses the different types of carbon compounds, including hydrocarbons, alcohols, carboxylic acids, and esters, and their properties and reactions.
The chapter explains the bonding and hybridization of carbon atoms, which are the basis for the formation of numerous organic compounds. It also highlights the importance of carbon compounds in the chemistry of life, such as carbohydrates, proteins, and nucleic acids.
Furthermore, the chapter discusses the different types of chemical reactions that carbon compounds can undergo, including substitution, addition, and oxidation-reduction reactions. It explains the mechanisms involved in these reactions and how they contribute to the formation of new organic compounds.
Overall, NCERT Solutions for Class X Science Chapter 4, Carbon and its Compounds, is an essential resource for students who want to gain a comprehensive understanding of the properties and reactions of carbon compounds. The solutions provided in this chapter help students to clear their doubts and understand the concepts thoroughly. It also provides a strong foundation for further studies in chemistry and related fields.

Frequently Asked Questions on NCERT Solutions for Class 10 Science Chapter 4

What type of questions are present in the Chapter 4 of NCERT Solutions for Class 10 Science?

The type of questions present in the Chapter 4 of NCERT Solutions for Class 10 Science are –
1. Multiple science questions – 3 questions
2. Short answer – 2 questions
3. Long answer – 7 questions
4. Very long answer – 3 questions

List out the topics present in the Chapter 4 of NCERT Solutions for Class 10 Science.

The topics present in the Chapter 4 of NCERT Solutions for Class 10 Science are –
1. Bonding in Carbon – The covalent bond
2. Versatile nature of carbon
3. Chemical properties of Carbon compounds
4. Some important carbon compounds – ethanol and ethanoic acid
5. Soaps and detergents

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