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CBSE · Class 12 · Chemistry

Alcohols, Phenols and Ethers

Standard difficulty · 20 questions · 40 marks

Name: Date: Score: ____ / 40

Show your working for Sections B and C. Answers are on the last page — try every question first!

Section A — Choose the correct answer8 × 1 = 8 marks
1.
Alcohols have higher boiling points than ethers of similar mass because of:
  1. ionic bonding
  2. lower molar mass
  3. van der Waals forces only
  4. hydrogen bonding
2.
The IUPAC name of (CH3)2CHOH is:
  1. propan-2-ol
  2. butan-2-ol
  3. 2-methylpropan-2-ol
  4. 2-methylpropan-1-ol
3.
Which alcohol gives turbidity at once with the Lucas reagent?
  1. propan-1-ol
  2. butan-1-ol
  3. ethanol
  4. 2-methylpropan-2-ol
4.
Ethanol is treated with pyridinium chlorochromate (PCC). The product is:
  1. no reaction (tertiary)
  2. butanal
  3. ethanal
  4. methanal
5.
The correct order of increasing acid strength is:
  1. 2-methylphenol < 2,4,6-trinitrophenol < ethanol
  2. 2-methylphenol < ethanol < 2,4,6-trinitrophenol
  3. ethanol < 2-methylphenol < 2,4,6-trinitrophenol
  4. 2,4,6-trinitrophenol < 2-methylphenol < ethanol
6.
Phenol reacts with NaOH, then CO2 under pressure, then acid (Kolbe). The product is:
  1. benzene
  2. benzoquinone
  3. salicylic acid (2-hydroxybenzoic acid)
  4. a mixture of 2-nitrophenol and 4-nitrophenol
7.
2-methoxypropane ((CH3)2CHOCH3) is heated with HI. The products are:
  1. CH3I and propan-2-ol
  2. phenol and C2H5I
  3. 2-iodo-2-methylpropane and CH3OH (SN1 at the tertiary carbon)
  4. CH3I and CH3OH (CH3I with excess HI)
8.
Assertion (A): Methanol gives turbidity at once with the Lucas reagent.
Reason (R): Alcohols react with the Lucas reagent through carbocations, so the order is tertiary > secondary > primary.
  1. Both A and R are true, and R is the correct explanation of A.
  2. Both A and R are true, but R is not the correct explanation of A.
  3. A is true, but R is false.
  4. A is false, but R is true.
Section B — Short answer8 × 2 = 16 marks
9.
Why is phenol acidic? Why is 4-nitrophenol more acidic than phenol?
10.
What is the main product when cyclohexanol is heated with concentrated H2SO4? Which alcohols dehydrate most easily?
11.
Give the IUPAC name and the common name of C6H5CH2OCH3.
12.
96.2 g of 2-methylpropan-2-ol reacts completely with sodium. What volume of hydrogen is given off at STP? (C = 12, H = 1, O = 16; 1 mol of gas = 22.4 L at STP)
13.
Arrange in increasing order of boiling point, and explain: pentane, methoxyethane, butan-1-ol.
14.
What is formed when 2-methylpropan-2-ol is oxidised with (a) PCC, (b) alkaline KMnO4, then acid?
15.
Write the product when phenol is treated with Na2Cr2O7 with H2SO4.
16.
Which alkoxide and which alkyl halide would you use to make tert-butyl methyl ether by the Williamson synthesis? Explain your choice.
Section C — Word problems4 × 4 = 16 marks
17.
Describe three methods of preparing alcohols, with equations.
18.
Identify the compounds in: methanal —CH3MgBr, then H2O→ A —PCC→ B.
19.
Arrange in increasing order of acid strength, and explain the effect of each substituent: 4-nitrophenol, 3-nitrophenol, phenol, 2-methylphenol.
20.
An alcohol of formula C4H9OH is butan-2-ol. Classify it, state what you see with the Lucas reagent, give its products with PCC and with acidified KMnO4, and find the volume of hydrogen at STP when 14.8 g of it reacts with sodium. (C = 12, H = 1, O = 16; 1 mol of gas = 22.4 L at STP)
AmbifulWorksheets
Practice that never repeats
CBSE · Class 12 · Chemistry

Answer key

Alcohols, Phenols and Ethers · AW-12C-APE-2026-V1 · For parents — fold back or tear off before handing the sheet to your child.

QAnswerWorking
1(d) hydrogen bonding—
2(a) propan-2-olthe longest chain containing the –OH carbon; –ol ending
3(d) 2-methylpropan-2-ol2-methylpropan-2-ol is a tertiary (3°) alcohol
4(c) ethanalPCC stops a primary alcohol at the aldehyde
5(c) ethanol < 2-methylphenol < 2,4,6-trinitrophenolpKa: 2,4,6-trinitrophenol 0.5, 2-methylphenol 10.2, ethanol 15.9 (lower pKa, stronger acid)
6(c) salicylic acid (2-hydroxybenzoic acid)—
7(a) CH3I and propan-2-olthe C–O bond to the smaller (or tertiary, by SN1) group breaks
8(d) A is false, but R is true.A is false: it is a primary (1°) alcohol. R is true.
9The phenoxide ion formed by losing H+ is stabilised by resonance over the ring. A nitro group at the para position withdraws electrons and spreads the negative charge further, stabilising the ion even more.—
10cyclohexene; tertiary > secondary > primaryacid-catalysed dehydration through a carbocation
11(methoxymethyl)benzene; benzyl methyl etherthe larger group is the parent; the smaller is alkoxy
1214.56 L2ROH + 2Na → 2RONa + H2; 1.3 mol of alcohol gives 0.65 mol of H2
13methoxyethane < pentane < butan-1-olalcohols and phenols form hydrogen bonds, ethers and alkanes do not; data (°C): pentane 36, methoxyethane 7, butan-1-ol 117
14(a) no reaction (tertiary); (b) no reaction under mild conditionsPCC is mild; alkaline KMnO4 takes a primary alcohol to the acid
15benzoquinonethe –OH group activates the ring at the ortho and para positions
16(CH3)3CONa and CH3Br; CH3ONa with (CH3)3CBr would give mainly 2-methylpropene by eliminationWilliamson synthesis is SN2: use the less hindered halide
17From alkenes by acid-catalysed hydration (Markovnikov): CH3CH=CH2 + H2O → CH3CH(OH)CH3. By hydroboration–oxidation (anti-Markovnikov): propene → propan-1-ol. From carbonyl compounds by reduction (H2/Pd, NaBH4, LiAlH4) or with Grignard reagents: HCHO gives a 1° alcohol, other aldehydes 2°, ketones 3°.—
18A = ethanol, B = ethanalfollow each reagent in turn
192-methylphenol < phenol < 3-nitrophenol < 4-nitrophenolnitro groups (especially ortho and para) withdraw electrons and stabilise the phenoxide ion; methyl groups release electrons and destabilise it; ethanol is weakest. pKa: 4-nitrophenol 7.1, 3-nitrophenol 8.3, phenol 10, 2-methylphenol 10.2
20secondary (2°); turbidity in about five minutes; butan-2-one; butan-2-one; 2.24 L of H2 (M = 74 g/mol)Lucas order 3° > 2° > 1°