CBSE Class 10 Science Chapter 4: Carbon and its Compounds NCERT Solutions
This comprehensive set of NCERT Solutions for CBSE Class 10 Science, Chapter 4, focuses on Carbon and its Compounds. It covers fundamental concepts such as the nature of covalent bonds, illustrated with examples like methane chloride (CH3Cl). The solutions also delve into identifying functional groups in organic molecules, as seen with butanone. Additionally, practical applications are discussed, including the reason for incomplete combustion in cooking vessels. The exercises provide practice in drawing electron dot structures for various organic compounds like ethanoic acid, propanone, and inorganic molecules like hydrogen sulfide (H2S) and fluorine (F2). These solutions are designed to help students grasp the essential principles of carbon chemistry and prepare effectively for their examinations by offering clear explanations and step-by-step problem-solving.
Quick info
| Board | CBSE |
|---|---|
| Class | Class 10 |
| Subject | Science |
| Session | 2026 |
| Language | English |
| Type | NCERT Solutions |
| Chapter | Chapter 4 |
Chapter summary
Chapter 4 of the CBSE Class 10 Science syllabus, 'Carbon and its Compounds,' is explored through these NCERT Solutions. The solutions clarify the formation and nature of covalent bonds, using examples like CH3Cl. They also cover the identification of functional groups in organic compounds, such as ketones in butanone, and explain phenomena related to combustion. The exercises include drawing electron dot structures for key molecules, reinforcing understanding of bonding and molecular structure in organic and inorganic chemistry.
Learning outcomes
- Understand the nature of covalent bonds and their formation.
- Identify functional groups in organic compounds.
- Explain the process of combustion and its implications.
- Draw electron dot structures for various organic and inorganic molecules.
- Relate molecular structure to compound properties.
Topics covered
Paper topics
- Carbon and its Compounds
- Covalent Bonding
- Electron Dot Structures
- Functional Groups
- Ketones
- Carboxylic Acids
- Aldehydes
- Alcohols
- Combustion
- Incomplete Combustion
- Ethanoic Acid
- Butanone
Important topics
- Nature of Covalent Bonds
- Electron Dot Structures
- Identification of Functional Groups
- Combustion of Fuels
- Structure of Ethanoic Acid
- Structure of Butanone
PDF preview
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Questions and Solutions
Question 1
(a) 6 covalent bonds.
(b) 7 covalent bonds.
(c) 8 covalent bonds.
(d) 9 covalent bonds.
Ethane has the molecular formula C<sub>2</sub>H<sub>6</sub>. Its structure consists of two carbon atoms single-bonded to each other and each carbon atom bonded to three hydrogen atoms. The structure can be visualized as H<sub>3</sub>C-CH<sub>3</sub>. This structure contains one carbon-carbon single bond and six carbon-hydrogen single bonds. Each single bond represents one covalent bond formed by the sharing of electrons. Therefore, the total number of covalent bonds in ethane is 1 (C-C) + 6 (C-H) = 7 covalent bonds.
The correct option is (b).
Question 2
(a) carboxylic acid.
(b) aldehyde.
(c) ketone.
(d) alcohol.
Butanone is an organic compound with the chemical formula C<sub>4</sub>H<sub>8</sub>O. The name 'butanone' indicates a four-carbon chain ('butan-') and the presence of a ketone functional group ('-one'). In a ketone, the carbonyl group (C=O) is located within the carbon chain, not at the end. For butanone, the carbonyl group is on the second carbon atom, making its structure CH<sub>3</sub>-CO-CH<sub>2</sub>-CH<sub>3</sub>. Therefore, the functional group of butanone is a ketone.
The correct option is (c).
Question 3
(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.
The blackening of the bottom of a cooking vessel is typically caused by soot, which is a product of incomplete combustion. Incomplete combustion occurs when a fuel does not burn completely, usually due to insufficient supply of oxygen. This results in the formation of unburnt carbon particles that deposit on the surface of the vessel. If the fuel were burning completely, it would produce primarily carbon dioxide and water, with minimal soot.
The correct option is (b).
Question 4
Carbon is an element that has four valence electrons. To achieve a stable electron configuration (an octet), carbon needs to gain or lose four electrons. However, gaining four electrons requires a large amount of energy, and losing four electrons also requires significant energy, making both processes energetically unfavorable and unstable for the carbon atom. Therefore, carbon achieves stability by sharing its valence electrons with other atoms, forming covalent bonds. In a covalent bond, electrons are shared between atoms, and the shared pair of electrons belongs to the valence shells of both participating atoms.
In chloromethane (CH<sub>3</sub>Cl), the carbon atom needs four electrons to complete its octet. Each of the three hydrogen atoms needs one electron to complete its duplet (a stable configuration for hydrogen), and the chlorine atom needs one electron to complete its octet.
To achieve stability, the carbon atom shares one electron each with three hydrogen atoms, forming three C-H covalent bonds. Additionally, the carbon atom shares one electron with the chlorine atom, forming a C-Cl covalent bond. The chlorine atom also shares one of its electrons with carbon. In total, carbon forms three single covalent bonds with hydrogen atoms and one single covalent bond with a chlorine atom. This sharing of electrons allows all atoms (carbon, hydrogen, and chlorine) to attain a stable electron configuration.
The electron dot structure would show the shared pairs of electrons between C and H, and between C and Cl, along with the lone pairs on the chlorine atom.
Question 5
- ethanoic acid.
- propanone.
- propanone.
- F<sub>2</sub>.
- ethanoic acid.
- H<sub>2</sub>S.
The question seems to have a mix-up in listing the compounds for electron dot structures. Based on the provided context, we will draw the electron dot structures for ethanoic acid, propanone, H<sub>2</sub>S, and F<sub>2</sub>.
(a) Ethanoic acid (CH<sub>3</sub>COOH):
Ethanoic acid has a structure with a methyl group (CH<sub>3</sub>) attached to a carboxyl group (-COOH). Carbon has 4 valence electrons, Hydrogen has 1, Oxygen has 6. The structure involves single bonds between C-C, C-H, C-O, O-H, and a double bond between C=O.
Electron Dot Structure for Ethanoic Acid:
Imagine the central carbon atom bonded to three hydrogen atoms and the other carbon atom. This second carbon atom is bonded to one oxygen atom with a single bond and to another oxygen atom with a double bond. This second oxygen atom is also bonded to a hydrogen atom.
[Visual representation of electron dot structure would be shown here, with dots representing valence electrons and shared pairs indicating covalent bonds. For example, the methyl carbon shares electrons with 3 H atoms and the carboxyl carbon. The carboxyl carbon shares electrons with the methyl carbon, one oxygen via a double bond, and the other oxygen via a single bond. The single-bonded oxygen shares electrons with the carboxyl carbon and a hydrogen atom, and has lone pairs. The double-bonded oxygen has lone pairs.]
(b) Propanone (CH<sub>3</sub>COCH<sub>3</sub>):
Propanone, also known as acetone, is a ketone with three carbon atoms. The central carbon atom is double-bonded to an oxygen atom (the ketone group), and single-bonded to two methyl groups (CH<sub>3</sub>).
Electron Dot Structure for Propanone:
The central carbon atom forms a double bond with an oxygen atom and single bonds with two methyl groups. Each methyl group consists of a carbon atom bonded to three hydrogen atoms.
[Visual representation: Central C double bonded to O. This C is also single bonded to two other C atoms. Each of these outer C atoms is single bonded to 3 H atoms. The double-bonded oxygen has lone pairs.]
(c) Hydrogen Sulfide (H<sub>2</sub>S):
Hydrogen sulfide consists of one sulfur atom and two hydrogen atoms. Sulfur has 6 valence electrons, and each hydrogen has 1 valence electron. Sulfur forms single covalent bonds with each of the two hydrogen atoms, and has two lone pairs of electrons.
Electron Dot Structure for H<sub>2</sub>S:
The sulfur atom is in the center, bonded to two hydrogen atoms via single covalent bonds. The remaining four valence electrons of sulfur form two lone pairs.
[Visual representation: S in the center, single bonded to two H atoms. S has two lone pairs of electrons.]
(d) Fluorine molecule (F<sub>2</sub>):
A fluorine molecule consists of two fluorine atoms. Each fluorine atom has 7 valence electrons. To achieve a stable octet, the two fluorine atoms share one pair of electrons, forming a single covalent bond between them. Each fluorine atom also has three lone pairs.
Electron Dot Structure for F<sub>2</sub>:
The two fluorine atoms are bonded together by a single covalent bond (one shared pair of electrons). Each fluorine atom has three lone pairs of electrons.
[Visual representation: Two F atoms bonded by a single bond. Each F atom has 3 lone pairs.]
Common mistakes
- Incorrectly counting covalent bonds in molecules.
- Misidentifying functional groups in organic compounds.
- Errors in drawing electron dot structures, especially with shared and lone pairs.
- Confusing complete and incomplete combustion.
Revision tips
- Focus on understanding the electron sharing mechanism in covalent bond formation.
- Practice drawing electron dot structures for all examples and exercises.
- Memorize common functional groups and their corresponding compound names.
- Review the conditions and products of complete vs. incomplete combustion.
Practice MCQs
Q1. Ethane (C2H6) is characterized by how many covalent bonds?
Explanation: Ethane (C2H6) has one C-C single bond and six C-H single bonds, totaling 7 covalent bonds.
Q2. What is the functional group present in butanone?
Explanation: Butanone is a four-carbon compound where the carbonyl group (C=O) is located within the carbon chain, indicating a ketone functional group.
Q3. Blackening of the bottom of a cooking vessel during cooking suggests:
Explanation: Black soot on the vessel bottom is a sign of incomplete combustion, where the fuel is not burning efficiently and producing carbon particles.
Q4. In the formation of CH3Cl, carbon shares electrons to achieve stability. This type of bonding is called:
Explanation: Carbon shares its valence electrons with hydrogen and chlorine atoms to form covalent bonds, completing its octet and achieving stability.
Q5. Which of the following molecules exhibits covalent bonding?
Explanation: Water (H2O) is formed by the sharing of electrons between oxygen and hydrogen atoms, resulting in covalent bonds.
Frequently asked questions
What is the main concept covered in CBSE Class 10 Science Chapter 4?
Chapter 4, 'Carbon and its Compounds,' primarily focuses on the unique properties of carbon, the formation of covalent bonds, different types of organic compounds, and their structures.
How do these NCERT Solutions help students?
These solutions provide clear, step-by-step explanations for each question, helping students understand complex concepts like covalent bonding and electron dot structures, and reinforcing their learning for exams.
What is a covalent bond, as explained in the solutions?
A covalent bond is formed when atoms share valence electrons to achieve a stable electron configuration, typically an octet. This sharing allows both atoms to effectively 'count' the shared electrons towards their stable state.
Why is the bottom of a cooking vessel blackened?
The blackening indicates incomplete combustion of the fuel. This happens when there isn't enough oxygen, or the fuel is not burning efficiently, leading to the formation of unburnt carbon particles (soot).
What are functional groups in organic chemistry?
Functional groups are specific groups of atoms within molecules that are responsible for the characteristic chemical reactions of those molecules. Examples include ketone, aldehyde, and carboxylic acid groups.
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