Alcohols, Phenols and Ethers: Class 12 Important Questions with Answers

Practice set: test yourself

Try every question before looking at the answers below. 64 or more out of 80 means you are ready for the board.

C. Very short answer (1 mark each)

1. IUPAC name of CH₃CH(OH)CH₃.
2. Name the reagent for 1° alcohol → aldehyde.
3. Write the formula of picric acid.
4. Name an allylic alcohol.
5. Which is more acidic: phenol or p-cresol?
6. Product of phenol + Zn dust.
7. Give one use of the Williamson synthesis.
8. What is denatured alcohol?
9. Name the reaction: phenol + CHCl₃ + NaOH.
10. What is the C–O–C angle in ethers roughly?

D. Short answer I (2 marks each)

1. Write the mechanism of hydration of propene (two steps shown).
2. Why is phenol more acidic than ethanol?
3. How will you distinguish 1°, 2°, 3° alcohols by the Lucas test?
4. Prepare 2-methylpropan-2-ol by a Grignard reaction.
5. Write the products of anisole with HI and with Br₂/CH₃COOH.
6. Why is o-nitrophenol steam volatile but not p-nitrophenol?
7. Give the preparation of phenol from cumene.
8. Why can't tert-butyl methyl ether be made from tert-butyl bromide and CH₃ONa?

Rough work

E. Short answer II (3 marks each)

1. Write the mechanism of dehydration of ethanol to ethene.
2. Arrange in increasing acidity, with reasons: phenol, ethanol, p-nitrophenol, p-cresol.
3. Write the Kolbe and Reimer–Tiemann reactions.
4. Convert: (a) propene → propan-1-ol (b) phenol → picric acid (c) ethanol → ethoxyethane.
5. Explain why phenols do not undergo C–O cleavage and alcohols do.
6. Write the products of HI with (a) CH₃OC₂H₅ (b) (CH₃)₃COCH₃ (c) C₆H₅OC₂H₅.

F. Long answer (5 marks each)

1. (a) Give three methods of preparing alcohols with equations. (b) How do 1°, 2° and 3° alcohols differ in oxidation? (c) Explain the Lucas test.
2. A compound C₂H₆O (A) reacts with Na, gives iodoform, and at 413 K with H₂SO₄ gives B (C₄H₁₀O). (a) Identify A and B. (b) Write the reactions. (c) What does B give with excess HI?

G. HOTS (higher-order thinking)

1. Why is the C–O bond in phenol shorter than in methanol?
2. Why is phenol nitrated without H₂SO₄ but benzene is not?
3. Why does butan-1-ol on dehydration give mainly but-2-ene?
4. Why is 2,4,6-trinitrophenol called picric "acid"?

20 MCQs

1. Most acidic
   (a) ethanol (b) phenol (c) p-nitrophenol (d) p-cresol
2. 2° alcohol + CrO₃ gives
   (a) ketone (b) aldehyde (c) acid (d) alkene
3. Lucas test is immediate with
   (a) 1° (b) methanol (c) 2° (d) 3°
4. Kolbe's reaction product
   (a) salicylaldehyde (b) salicylic acid (c) benzoic acid (d) phenol
5. Phenol + Br₂ water
   (a) o-bromophenol (b) 2,4,6-tribromophenol (c) p-bromophenol (d) bromobenzene
6. Anisole + HI
   (a) C₆H₅I + CH₃OH (b) C₆H₅CH₃ (c) C₆H₆ + CH₃I (d) C₆H₅OH + CH₃I
7. Steam volatile
   (a) o-nitrophenol (b) p-nitrophenol (c) picric acid (d) phenol
8. RMgX + HCHO then H₂O gives
   (a) 2° alcohol (b) 3° alcohol (c) 1° alcohol (d) ketone
9. Ethanol at 443 K with conc H₂SO₄
   (a) ether (b) ethyl hydrogensulphate only (c) ethanal (d) ethene
10. Slow step of dehydration forms
    (a) protonated alcohol (b) carbocation (c) carbanion (d) radical
11. Williamson synthesis is
    (a) SN1 (b) E1 (c) SN2 (d) electrophilic addition
12. Phenol from cumene also gives
    (a) acetone (b) methanol (c) ethanal (d) benzene
13. Phenol + Zn dust
    (a) cyclohexanol (b) benzene (c) toluene (d) biphenyl
14. Reagent: 1° alcohol → aldehyde
    (a) KMnO₄ (b) NaBH₄ (c) PCC (d) LiAlH₄
15. Hydroboration–oxidation of propene gives
    (a) propan-2-ol (b) propane (c) propanal (d) propan-1-ol
16. Strongest base
    (a) C₂H₅O⁻ (b) C₆H₅O⁻ (c) OH⁻ (d) CH₃COO⁻
17. Br₂ in CS₂ with phenol at 273 K
    (a) o- and p-bromophenol (b) 2,4,6-tribromophenol (c) m-bromophenol (d) no reaction
18. Highest b.p.
    (a) CH₃OCH₃ (b) CH₃Cl (c) C₃H₈ (d) C₂H₅OH
19. Reimer–Tiemann intermediate group
    (a) –CH₂Cl (b) –CHCl₂ (c) –CCl₃ (d) –COCl
20. Aspirin is made from
    (a) phenol (b) benzoic acid (c) salicylic acid (d) salicylaldehyde

1 (c) · 2 (a) · 3 (d) · 4 (b) · 5 (b) · 6 (d) · 7 (a) · 8 (c) · 9 (d) · 10 (b) · 11 (c) · 12 (a) · 13 (b) · 14 (c) · 15 (d) · 16 (a) · 17 (a) · 18 (d) · 19 (b) · 20 (c)

Assertion–Reason (6)

(a) Both true, R explains A. (b) Both true, R does not explain A. (c) A true, R false. (d) A false, R true.

1. A: Phenol is more acidic than ethanol. R: Phenoxide ion is resonance stabilised.
2. A: 3° alcohols are not oxidised easily. R: They have no α-hydrogen.
3. A: o-Nitrophenol has a lower b.p. than p-nitrophenol. R: o-Nitrophenol has intermolecular H-bonds.
4. A: Alkyl aryl ethers cleave at the alkyl–O bond with HI. R: The aryl–O bond has partial double-bond character.
5. A: Ethers are less soluble than isomeric alcohols. R: Ethers cannot form H-bonds with water at all.
6. A: –OH group is o/p directing. R: It shows +R effect.

Key: 1 (a) · 2 (a) · 3 (c) · 4 (a) · 5 (c) · 6 (a)

Answers to the practice set