30 Very Short Questions & Answers

Keep answers crisp — each Q is followed by a one-line answer for fast recall.

1. 1. What is tetravalency of carbon?
   Carbon can form four covalent bonds because it has four valence electrons.
2. 2. What is catenation?
   Ability of carbon to form long chains by bonding with itself.
3. 3. Define homologous series.
   A family of compounds with same functional group and successive members differing by CH₂.
4. 4. Give one example of structural isomerism.
   C₄H₁₀ exists as n‑butane and isobutane (branched isomer).
5. 5. What is the functional group of alcohols?
   —OH (hydroxyl) group.
6. 6. What is the functional group of carboxylic acids?
   —COOH (carboxyl) group.
7. 7. Write the IUPAC name of CH₃CH₂OH.
   Ethanol.
8. 8. Write the IUPAC name of CH₃COOH.
   Ethanoic acid.
9. 9. What is esterification?
   Reaction of alcohol with carboxylic acid producing an ester and water (acid catalyst).
10. 10. Give the product of CH₃CH₂OH + CH₃COOH.
    Ethyl ethanoate (an ester) + H₂O.
11. 11. What is saponification?
    Hydrolysis of fats/oils by NaOH producing glycerol and soap (fatty acid salts).
12. 12. Why do alcohols have higher boiling points than hydrocarbons of similar molar mass?
    Because alcohols form hydrogen bonds which increase boiling points.
13. 13. Why is ethanol miscible with water?
    Due to hydrogen bonding between —OH of ethanol and water molecules.
14. 14. What is the general formula for alkanes?
    CₙH₂ₙ₊₂.
15. 15. Name the simplest alkane.
    Methane (CH₄).
16. 16. Name the simplest alkene.
    Ethene (C₂H₄).
17. 17. What type of bond is present in ethene between carbon atoms?
    A double covalent bond (π and σ bonds).
18. 18. Give a use of esters.
    Used in perfumes and flavouring due to fruity smells.
19. 19. What are soaps chemically?
    Sodium or potassium salts of long‑chain fatty acids.
20. 20. How do detergents differ from soaps?
    Detergents are sulphonates and work in hard water; soaps form scum with Ca²⁺/Mg²⁺.
21. 21. What is complete combustion of carbon compounds?
    Burning in excess oxygen to produce CO₂ and H₂O.
22. 22. What toxic product forms in incomplete combustion?
    Carbon monoxide (CO).
23. 23. What happens when primary alcohol is oxidised?
    It forms an aldehyde and can further oxidise to a carboxylic acid.
24. 24. What is the functional group of aldehydes?
    —CHO (formyl) group.
25. 25. What is the functional group of ketones?
    —C(=O)— (carbonyl) within the chain; example: propanone.
26. 26. State one physical property of carboxylic acids.
    They are generally higher boiling and soluble in water (short chains) due to H‑bonding.
27. 27. What reagent is commonly used as an acid catalyst in esterification?
    Concentrated sulfuric acid (H₂SO₄).
28. 28. Give an example of a naturally occurring ester.
    Ethyl acetate occurs in some fruits and contributes to their aroma.
29. 29. Define isomerism in one line.
    Same molecular formula but different structural arrangement of atoms.
30. 30. Why is carbon unique in forming large diverse compounds?
    Due to tetravalency, small size, and ability to catenate, enabling strong C–C bonds and varied structures.

Tip: Use this list for quick daily revision — try to answer aloud before reading the one-line answer for active recall.