Short Questions Answer
1. What is catenation?
Answer: The ability of carbon to form long chains and rings by bonding with other carbon atoms.
2. Why are most carbon compounds poor conductors of electricity?
Answer: Because they are covalently bonded and do not contain ions.
3. What type of bond is formed in methane (CH₄)?
Answer: Single covalent bonds between carbon and hydrogen atoms.
4. Name the three allotropes of carbon.
Answer: Diamond, graphite, and fullerene.
5. What is the functional group in alcohols?
Answer: –OH (hydroxyl group).
6. Define homologous series.
Answer: A series of organic compounds having the same functional group and similar chemical properties, differing by a –CH₂– unit.
7. What are saturated hydrocarbons?
Answer: Compounds having only single bonds between carbon atoms.
8. What are unsaturated hydrocarbons?
Answer: Compounds having double or triple bonds between carbon atoms.
9. What is the general formula of alkanes?
Answer: CₙH₂ₙ₊₂
10. What is the main product formed when ethanol reacts with sodium?
Answer: Sodium ethoxide and hydrogen gas.
11. What is the molecular formula of ethanoic acid?
Answer: CH₃COOH
12. What happens when ethanoic acid reacts with sodium carbonate?
Answer: It produces sodium acetate, carbon dioxide, and water.
13. What is hydrogenation?
Answer: The addition of hydrogen to unsaturated hydrocarbons in the presence of catalysts like nickel or palladium.
14. Why is graphite a good conductor of electricity?
Answer: Because it has free electrons in its layers that can move easily.
15. What is the difference between soap and detergent?
Answer: Soap is a sodium/potassium salt of carboxylic acid, while detergent is a sodium salt of sulphonic acid and works in hard water.
Long Questions Answer
1. Explain the versatile nature of carbon.
Answer: Carbon forms a large number of compounds due to:
(i) Catenation – ability to form long chains and rings.
(ii) Tetravalency – can form four covalent bonds with other atoms.
(iii) Small size – forms strong and stable covalent bonds with other elements.
2. Differentiate between saturated and unsaturated hydrocarbons with examples.
Answer: Saturated hydrocarbons contain single bonds only (e.g., methane – CH₄, ethane – C₂H₆).
Unsaturated hydrocarbons contain double or triple bonds (e.g., ethene – C₂H₄, ethyne – C₂H₂).
3. Explain the chemical properties of ethanol.
Answer: (i) Reaction with sodium: produces sodium ethoxide and hydrogen gas.
(ii) Dehydration: in presence of concentrated H₂SO₄, ethanol forms ethene.
(iii) Solubility: completely miscible with water and used as solvent.
4. Describe the properties and uses of ethanoic acid.
Answer: (i) Weak acid; (ii) Used in making vinegar and esters; (iii) Reacts with bases to form salts; (iv) Melting point 290 K (glacial acetic acid).
5. Explain the formation and cleaning action of soap.
Answer: Soap molecules have a hydrophobic tail and hydrophilic head. They form micelles that trap oily dirt inside and wash it away with water.
6. What happens during the combustion of carbon compounds?
Answer: Carbon compounds burn in oxygen to produce CO₂, water, and heat.
Example: CH₄ + 2O₂ → CO₂ + 2H₂O + energy.
7. Explain oxidation and addition reactions with examples.
Answer: Oxidation: Addition of oxygen (ethanol → ethanoic acid).
Addition: Hydrogen adds to unsaturated hydrocarbons (ethene + H₂ → ethane).
8. What are functional groups? Give examples.
Answer: Specific atoms/groups in organic compounds that determine their properties.
Examples: OH (alcohol), –COOH (acid), –CHO (aldehyde), –CO– (ketone), –Cl (halo group).
9. Explain how homologous series shows a gradation in properties.
Answer: Members differ by a –CH₂– unit; as molecular mass increases, melting and boiling points increase, but chemical properties remain similar.
10. Describe the difference between soaps and detergents and their action in hard water.
Answer: Soaps form scum with calcium and magnesium ions in hard water, reducing effectiveness.
Detergents do not form scum and remain effective even in hard water.
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