Class 10 Science: Carbon and its Compounds important questions

Carbon and its Compounds is a chapter of Class 10 Science for the Andhra Pradesh State Board. These 15 questions are marked Very Important, Important or Practice, and each answer has been checked by our team. Use them to revise, not as a prediction of what will come in the exam.

1. Important · 4 marks

   1. Write any four uses of carbon and its allotropes.

   1) Diamond: the hardest natural substance, used in tools for cutting glass and drilling rocks, and in jewellery. 2) Graphite: a good conductor, used for electrodes; soft and slippery, used as a lubricant and in pencil leads. 3) Fullerenes (C₆₀) are being studied for use in medicine and electronics. 4) Carbon compounds such as coal, petroleum, natural gas and wood are used as fuels.

2. Practice · 1 marks

   2. Write any one use of a carbon compound.

   Ethanol is used as a fuel and as a solvent (and in medicines such as cough syrups and tinctures). Methane (CNG) is used as a fuel.

3. Important · 2 marks

   3. Which of these hydrocarbons undergo addition reactions: C₂H₆, C₃H₈, C₃H₆, C₂H₂, CH₄?

   C₃H₆ (propene, with a double bond) and C₂H₂ (ethyne, with a triple bond). They are unsaturated, so they undergo addition reactions. C₂H₆, C₃H₈ and CH₄ are saturated alkanes.

4. Practice · 1 marks

   4. How do you appreciate the role of soap in daily life?

   Soap removes oily dirt and germs from our hands, bodies and clothes, so it keeps us clean and helps prevent the spread of disease.

5. Very Important · 8 marks

   5. Explain how methane reacts with chlorine in sunlight, step by step, to give carbon tetrachloride.

   This is a substitution reaction: in sunlight, chlorine atoms replace hydrogen atoms of methane one at a time. CH₄ + Cl₂ → CH₃Cl (chloromethane) + HCl CH₃Cl + Cl₂ → CH₂Cl₂ (dichloromethane) + HCl CH₂Cl₂ + Cl₂ → CHCl₃ (chloroform) + HCl CHCl₃ + Cl₂ → CCl₄ (carbon tetrachloride) + HCl Each step replaces one more hydrogen, until all four are replaced.

6. Practice · 1 marks

   6. Which hydrocarbon undergoes an addition reaction? A) C₂H₆ B) C₃H₈ C) CH₄ D) C₃H₆

   D) C₃H₆ (propene). It is unsaturated (has a C=C double bond), so it can add hydrogen or other molecules. The others are saturated alkanes.

7. Important · 2 marks

   7. What two properties of carbon lead to the huge number of carbon compounds around us?

   1) Catenation: carbon atoms can link with each other to form long chains, branched chains and rings. 2) Tetravalency: a carbon atom has a valency of 4, so it can bond with four other atoms (carbon, hydrogen, oxygen, nitrogen and others).

8. Practice · 1 marks

   8. Write the formula of the first member of the homologous series to which C₅H₁₀ belongs.

   C₅H₁₀ fits CₙH₂ₙ, the alkene series. The first member is ethene, C₂H₄.

9. Important · 2 marks

   9. Explain combustion with an example.

   Combustion is the burning of a substance in oxygen, giving out heat and light. Carbon and its compounds burn to give carbon dioxide and water. Example: CH₄ + 2O₂ → CO₂ + 2H₂O + heat and light (burning of natural gas).

10. Practice · 1 marks

    10. A 5–8% solution of acetic acid in water is called ________.

    Vinegar.

11. Important · 2 marks

    11. Name all the possible structural isomers of C₄H₁₀.

    There are two: 1) n-butane: CH₃–CH₂–CH₂–CH₃ (straight chain) 2) isobutane (2-methylpropane): CH₃–CH(CH₃)–CH₃ (branched chain)

12. Very Important · 8 marks

    12. Complete the table of formulae (alkane, alkene, alkyne) for hydrocarbons with 3, 4, 5 and 6 carbon atoms.

    Alkane CₙH₂ₙ₊₂, alkene CₙH₂ₙ, alkyne CₙH₂ₙ₋₂: 3 carbons: C₃H₈, C₃H₆, C₃H₄ 4 carbons: C₄H₁₀, C₄H₈, C₄H₆ 5 carbons: C₅H₁₂, C₅H₁₀, C₅H₈ 6 carbons: C₆H₁₄, C₆H₁₂, C₆H₁₀

13. Practice · 1 marks

    13. Ethane, C₂H₆, has ___ covalent bonds. A) 6 B) 7 C) 8 D) 9

    B) 7: one C–C bond and six C–H bonds.

14. Important · 2 marks

    14. Name any two allotropes of carbon.

    Diamond and graphite. (Fullerenes, such as buckminsterfullerene C₆₀, are another.)

15. Very Important · 8 marks

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

    A soap molecule has two ends: a long hydrocarbon tail that is hydrophobic (dissolves in oil), and an ionic head that is hydrophilic (dissolves in water). In water, the tails point inwards and stick to the oily dirt, while the heads face outwards towards the water. This forms clusters called micelles, with the oil trapped in the centre. The micelles stay suspended in water as an emulsion, so when the cloth is rinsed, the dirt is washed away.