CBSE Class 10 Science Chapter 4: Carbon and its Compounds NCERT Solutions

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NCERT Solutions PDF Class 10 PDF

This chapter delves into the fascinating world of Carbon and its Compounds, a fundamental topic in Class 10 Science. The NCERT Solutions provide clear explanations and step-by-step problem-solving for exercises related to carbon's unique bonding properties, including covalent bonds and the formation of various organic molecules. Students will explore concepts like functional groups, nomenclature of carbon compounds, and the reasons behind carbon's versatility in forming a vast number of compounds. These solutions are designed to help students grasp the core principles of organic chemistry, understand the structure and properties of carbon-based molecules, and prepare effectively for their board examinations by reinforcing key concepts and problem-solving techniques.

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BoardCBSE
ClassClass 10
SubjectScience
Session2026
LanguageEnglish
TypeNCERT Solutions
ChapterChapter 4: Carbon and its Compounds

Chapter summary

Chapter 4, Carbon and its Compounds, focuses on the unique properties of carbon that enable it to form a vast array of organic molecules. This NCERT Solutions set covers the nature of covalent bonding, the formation of single, double, and triple bonds, and the structure of simple carbon compounds. It also introduces functional groups, nomenclature, and the differences between saturated and unsaturated hydrocarbons. The solutions aim to build a strong foundation in understanding the basic principles of organic chemistry.

Learning outcomes

  • Understand the nature of covalent bonding in carbon compounds.
  • Identify and explain the role of functional groups in organic molecules.
  • Draw electron dot structures for simple carbon compounds.
  • Explain the reasons for the extensive bonding of carbon.
  • Differentiate between complete and incomplete combustion of fuels.

Topics covered

Paper topics

  • Carbon and its Compounds
  • Covalent Bonding
  • Electron Dot Structures
  • Valency of Carbon
  • Formation of Covalent Bonds
  • Structure of CH3Cl
  • Functional Groups
  • Ketones
  • Carboxylic Acids
  • Aldehydes
  • Alcohols
  • Combustion of Fuels

Important topics

  • Nature of Covalent Bonds
  • Electron Dot Structures
  • Functional Groups Identification
  • Combustion of Fuels

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Questions and Solutions

Question 1

Ethane, with the molecular formula C<sub>2</sub>H<sub>6</sub>, has how many covalent bonds in total?
Solution:

Ethane (C<sub>2</sub>H<sub>6</sub>) consists of two carbon atoms and six hydrogen atoms. The structure of ethane involves a single bond between the two carbon atoms (C-C) and six single bonds between each carbon atom and the hydrogen atoms (C-H). Each single bond represents one covalent bond formed by the sharing of electrons. Therefore, there is 1 C-C covalent bond and 6 C-H covalent bonds, making a total of 1 + 6 = 7 covalent bonds.

The correct option is (b) 7 covalent bonds.

Question 2

Butanone is a four-carbon compound. What is its functional group?
Solution:

Butanone is an organic compound with four carbon atoms. The suffix '-one' in its name indicates the presence of a ketone functional group. A ketone functional group consists of a carbonyl group (C=O) where the carbon atom is bonded to two other carbon atoms. In butanone, the carbonyl group is located at the second carbon atom of the four-carbon chain.

The correct option is (c) ketone.

Question 3

When cooking, if the bottom of the vessel gets blackened on the outside, what does this observation imply about the fuel being used?
Solution:

The blackening of the bottom of a cooking vessel is typically caused by the deposition of soot, which is a product of incomplete combustion. When a fuel does not burn completely, it produces unburnt carbon particles (soot) along with carbon dioxide and water. This incomplete combustion often occurs when there is insufficient oxygen supply or when the fuel is not vaporized properly. Therefore, a blackened vessel indicates that the fuel is not burning completely.

The correct option is (b) the fuel is not burning completely.

Question 4

Explain the nature of the covalent bond using the bond formation in chloromethane (CH<sub>3</sub>Cl).
Solution:

Carbon has an atomic number of 6 and its electronic configuration is 2, 4. It has 4 valence electrons. To achieve a stable octet (8 valence electrons), carbon can either gain 4 electrons or lose 4 electrons. However, gaining 4 electrons requires a large amount of energy to overcome the repulsion between the incoming electrons and the existing electrons, while losing 4 electrons also requires a substantial amount of energy. Therefore, carbon achieves stability by sharing its 4 valence electrons with other atoms, forming covalent bonds.

In chloromethane (CH<sub>3</sub>Cl), carbon needs 4 electrons to complete its octet. Each of the three hydrogen atoms needs 1 electron to complete its duplet (2 electrons), and chlorine (atomic number 17, electronic configuration 2, 8, 7) needs 1 electron to complete its octet.

Carbon shares one electron with each of the three hydrogen atoms, forming three C-H single covalent bonds. Carbon also shares one of its electrons with the chlorine atom, and the chlorine atom shares one of its valence electrons with carbon, forming a C-Cl single covalent bond. In this process, the shared electrons are counted towards the valence shell of both atoms involved in the bond. As a result, carbon achieves an octet (4 shared pairs = 8 electrons), and each hydrogen achieves a duplet (1 shared pair = 2 electrons), and chlorine achieves an octet (3 lone pairs + 1 shared pair = 8 electrons). This sharing of electrons to form stable bonds is the essence of covalent bonding.

Question 5

Draw the electron dot structures for:
  1. ethanoic acid
  2. propanone
  3. H<sub>2</sub>S
  4. F<sub>2</sub>
Solution:

To draw electron dot structures, we represent valence electrons as dots around the atomic symbol and show the sharing of electrons to form covalent bonds.

  1. Ethanoic acid (CH<sub>3</sub>COOH):

    Carbon (C) has 4 valence electrons, Hydrogen (H) has 1, and Oxygen (O) has 6. The structure has a CH<sub>3</sub> group attached to a carboxyl group (-COOH).

    The first carbon atom forms 3 single bonds with 3 hydrogen atoms and 1 single bond with the second carbon atom. The second carbon atom forms a double bond with one oxygen atom and a single bond with another oxygen atom, which is also bonded to a hydrogen atom.

    Electron dot structure of ethanoic acid

  2. Propanone (CH<sub>3</sub>COCH<sub>3</sub>):

    Propanone has three carbon atoms. The middle carbon atom is double-bonded to an oxygen atom (ketone group), and the two end carbon atoms are single-bonded to the middle carbon and also bonded to three hydrogen atoms each.

    Electron dot structure of propanone

  3. Hydrogen sulfide (H<sub>2</sub>S):

    Sulfur (S) has 6 valence electrons, and Hydrogen (H) has 1. The sulfur atom is bonded to two hydrogen atoms via single covalent bonds. The remaining 4 valence electrons of sulfur form two lone pairs.

    Electron dot structure of hydrogen sulfide

  4. Fluorine (F<sub>2</sub>):

    Each fluorine atom (F) has 7 valence electrons. In the F<sub>2</sub> molecule, the two fluorine atoms share one pair of electrons to form a single covalent bond. Each fluorine atom also has 3 lone pairs of electrons.

    Electron dot structure of fluorine molecule

Common mistakes

  • Incorrectly counting covalent bonds in molecules.
  • Misidentifying functional groups in organic compounds.
  • Errors in drawing electron dot structures.
  • Confusing complete and incomplete combustion.

Revision tips

  • Practice drawing electron dot structures for various carbon compounds.
  • Memorize common functional groups and their corresponding names.
  • Review the concept of covalent bonding and electron sharing.
  • Understand the conditions leading to complete and incomplete combustion.

Practice MCQs

Q1. Which of the following best describes the bonding in ethane (C2H6)?

Q2. Butanone is an organic compound characterized by which functional group?

Q3. Blackening of the bottom of a cooking vessel during cooking typically indicates:

Q4. In the formation of CH3Cl, carbon shares electrons to achieve stability. What is the primary reason for this sharing?

Q5. Which of the following represents the electron dot structure of F2?

Frequently asked questions

What is the main characteristic of carbon that allows it to form so many compounds?

Carbon's ability to form four covalent bonds, its valency of four, and its capacity to bond with itself (catenation) allow it to form a vast number of diverse compounds.

Why does carbon form covalent bonds instead of ionic bonds?

Carbon has a relatively small size and requires a significant amount of energy to either gain four electrons or lose four electrons. Therefore, it prefers to share its valence electrons with other atoms to form stable covalent bonds.

What does the blackening of a cooking vessel indicate about the fuel?

The blackening of the vessel's bottom suggests that the fuel is not burning completely. This incomplete combustion produces soot (carbon particles), which deposits on the vessel.

How can I draw the electron dot structure for ethanoic acid?

To draw the electron dot structure for ethanoic acid (CH3COOH), you need to determine the total number of valence electrons, arrange the atoms according to their connectivity, and then show the sharing of electrons to form single and double covalent bonds, ensuring each atom achieves a stable electron configuration.

What is the functional group in butanone?

Butanone is a ketone. Its functional group is the carbonyl group (C=O) where the carbon atom is bonded to two other carbon atoms.

How do these NCERT solutions help in exam preparation?

These solutions provide clear, step-by-step explanations for each question, reinforcing understanding of key concepts like covalent bonding and functional groups. Practicing with these rewritten solutions helps in mastering problem-solving techniques and identifying potential areas of error.

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