Class 10 Science Chapter 4
Carbon and its Compounds
Important Questions

Here are some critical Chapter 4 Carbon and its Compounds problems for Class 10 Science. These inquiries are intended to aid students in studying for and performing well on the CBSE Class 10 Science Examination 2023–24. Students can clear up their concerns and be ready for the exams by practising different types of questions. By answering these questions, you'll increase your confidence while also sharpening your problem-solving abilities. 

Introduction

In Chapter 4 of Carbon and its Compounds you will learn about The Covalent Bond, Versatile Nature of Carbon,Chemical Properties of Carbon Compounds,Important Carbon Compounds-Ethanol and Ethanoic Acid,Soaps and Detergents.

Class 10 Carbon and its Compounds Important Questions and Answers

Q 1. Identify the unsaturated compounds from the following:
(i) Propane
(ii) Propene
(iii) Propyne
(iv) Chloropropane

Options

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

Ans. (d)

Explanation:
Alkanes are known as saturated compounds. All the alkenes and alkynes with double and triple bonds in their carbon atoms are known as unsaturated alkenes. So propene and propyne are unsaturated compounds.

Q 2.  By how much atomic mass unit successive members of a homologous series vary?

Options

(a) One
(b) Sixteen
(c) Fourteen
(d) Twelve

Ans. (c)

Explanation:
The successive members of a homologous series differ by a CH₂ group. The molecular mass of a CH₂ group is 14 amu. Hence, each successive homologue of a homologous series differs by a mass of 14 amu.

Q 3. What is the difference in molecular formula of any two consecutive members of a homologous series?

Explanation:
The molecular formula of two consecutive members of a homologous series differ by CH₂.

Q 4. Two properties of carbon which lead to the formation of a large number of carbon compounds.

Explanation:
Catenation and tetravalency are the two properties of carbon which leads to the formation of a large number of carbon compounds.

Q 5. (i) Name the compound formed when ethanol is heated at 443 K in the presence of conc. H₂SO₄ and draw its electron dot structure.
State the role of conc.H₂SO₄ in this reaction.
(ii) What is hydrogenation? Explain it with the help of a chemical equation. State the role of this reaction in industry.

Explanation:
(i) Ethene is formed when ethanol at 443K is heated with excess concentrated sulphuric acid.
The mechanism of acid dehydration of ethanol to yield ethene is:
1. First step is the protonation of the oxygen atom of the −OH group.
2. Second step is the loss of a molecule of water to form carbonium ions.
3. Last step is deprotonation to form a carbon- carbon double bond.

Concentrated sulphuric acid can act as a dehydrating agent. Hence, ethanol when heated at 433 K with excess conc. H₂SO₄ undergoes a dehydration reaction to form ethene.
(ii) Hydrogenation is the process of addition between hydrogen and other compounds in presence of a catalyst.
For example: Alkene can be converted to alkane by using H₂ in presence of metal catalyst such as Pt, Ni or Pd
CH₂ = CH₂ → CH₃CH₃
The industrial applications are as follows:
1. To convert alkenes into alkanes.
2. To prepare vegetable ghee from vegetable oils.

CBSE Class 10 Science Chapter wise Important Questions

Conclusion

oswal.io offers a thorough set of questions for learning the topic in a better way if you're looking to further practise and improve your grasp of the concepts covered in the chapter.

Frequently Asked Questions

Q1: Covalent compounds have low melting and boiling point. Why?

Ans: Covalent compounds have low melting and boiling points because the forces of attraction between molecules of covalent compounds are very weak. On applying a small amount of heat these molecular forces break.

Q2: Write the next homologue of each of the following:
(i) C₂H₄
(ii) C₄H₆

Ans: (i) C₂H₄ belongs to alkene series having a general formula, C_nH_2n.Thus, next homologue will be C₃H_2×3 = C₃H_6
‍(ii) C4H6 belongs to the alkyne series having general formula, C_nH_2n-2.Thus, next homologue will be C₅H_2×5-2 = C₅H₈

Q3: Elements forming ionic compounds attain noble gas electronic configuration by either gaining or losing electrons from their valence shells. Explain the reason why carbon cannot attain such a configuration in this manner to form its compounds. Name the type of bonds formed in ionic compounds and in the compounds formed by carbon. Also explain with reason why carbon compounds are generally poor conductors of electricity.

Ans: Ionic compounds are formed either by gaining or losing electrons from the outermost shells, but carbon which has four electrons in its outermost shell cannot form ionic bonds because
1. If carbon forms ionic bonds by gaining four electrons to attain a noble gas configuration then it would be difficult for six protons in the nucleus to hold ten electrons.
2. If carbon forms ionic bonds by loss of four electrons then it would require a lot of energy to remove these electrons from the outermost shell.
Due to these reasons carbon forms covalent bonds by sharing the valence electrons.
Type of bonds formed in ionic compounds are called electrovalent bonds and the type of bonds formed in carbon compounds are called covalent bonds.

Q4: Give reasons for the following:
(i) Element carbon forms compounds mainly by covalent bonding.
(ii) Diamonds have a high melting point.
(iii) Graphite is a good conductor of electricity

Ans: (i) As carbon has four valence electrons and it can neither lose nor gain our electrons thus, it attains noble gas configuration only by sharing of electrons. I bus, it forms covalent compounds.
(ii) In diamond, each carbon atom is bonded to four other carbon atoms forming a rigid three-dimensional structure. This makes diamond the hardest known substance. Thus, it has a high melting point.
(iii) In graphite, each carbon atom is bonded to three other carbon atoms by covalent bonds in the same plane giving a hexagonal array. Thus, only three valence electrons are used for bond formation and hence, the fourth valence electron is free to move. As a result, graphite is a good conductor of electricity.

Q5: What are covalent bonds? Show their formation with the help of electron dot structure of methane. Why are covalent compounds generally poor conductors of electricity?

Ans: Covalent bonds are those bonds which are formed by sharing of the valence electrons between two atoms. Electron dot structure of methane is shown in the figure.

Covalent compounds are generally poor conductors ol electricity because they do not have tree electrons or ions.