Take timed practice tests on Alcohols, Phenols and Ethers for JEE Main and JEE Advanced with session-wise drills, score review, and explanation-led revision.
Six 20-question timed sessions plus a 60-question chapter module. Each item is original and reframed for copyright safety.
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1. Primary alcohols are oxidised to:
Explanation: Primary alcohols: R−CH₂OH → [O] → R−CHO (aldehyde) → [O] → R−COOH (carboxylic acid). Mild oxidation (PCC) stops at aldehyde; strong oxidation (KMnO₄, K₂Cr₂O₇) gives acid.
2. Which alcohol reacts immediately with Lucas reagent (ZnCl₂/HCl) at room temperature?
Explanation: Lucas test distinguishes 1°, 2°, 3° alcohols. Tertiary alcohols react immediately (turbidity at once) — they form stable 3° carbocations. Secondary react in 5 min. Primary react only on heating.
3. Phenol is more acidic than aliphatic alcohols because:
Explanation: Phenoxide (C₆H₅O⁻) is resonance-stabilised — the negative charge delocalises over the ortho and para positions of the ring. Aliphatic alkoxide ions have no such stabilisation.
4. Williamson's synthesis produces ethers from:
Explanation: Williamson synthesis: NaOR' + RX → R'−O−R + NaX. It is an SN2 reaction — works best with primary alkyl halides and is the best method for unsymmetrical ethers.
5. Phenol can be distinguished from alcohol by:
Explanation: Phenol reacts with FeCl₃ to give a characteristic violet/purple colour (ferric phenoxide complex). Alcohols do not give this test.
6. Phenol reacts with Br₂(aq) to give:
Explanation: Phenol is so strongly activated by −OH (+M effect) that it reacts with Br₂ in water (no catalyst needed) to give 2,4,6-tribromophenol as a white precipitate. This is used as a test for phenol.
7. Sodium phenoxide + CO₂ at 125°C and pressure gives (Kolbe reaction):
Explanation: Kolbe reaction: C₆H₅ONa + CO₂ → (125°C, 5 atm) → sodium 2-hydroxybenzoate (salicylate). Acidification gives salicylic acid, precursor to aspirin (acetylsalicylic acid).
8. The correct order of boiling points is:
Explanation: Alcohols have high boiling points due to H-bonding (n-BuOH bp = 117°C). Ethers have dipole-dipole interactions but no H-H bonding (Et₂O bp = 34.6°C). Alkanes have only London forces (butane bp = −1°C). Order: alcohol > ether > alkane.
9. Cleavage of ethers with HI proceeds by:
Explanation: Ether cleavage: R−O−R' + HI → ROH + R'I (or RI + R'OH). With I⁻ as nucleophile and H⁺ protonating O first, SN2 occurs on the less sterically hindered (smaller) alkyl group. With 3° groups, SN1 occurs.
10. Reimer-Tiemann reaction on phenol gives:
Explanation: Reimer-Tiemann reaction: phenol + CHCl₃ + NaOH → ortho-hydroxybenzaldehyde (salicylaldehyde) as major product + para isomer as minor. CHCl₃ forms :CCl₂ (dichlorocarbene) as the electrophile.
11. The functional group present in ethanol is:
Explanation: Ethanol (CH₃CH₂OH) contains the −OH (hydroxyl) functional group, which classifies it as an alcohol.
12. Victor Meyer's test is used to distinguish:
Explanation: Victor Meyer's test: treat alcohol with HI then PI₃, treat with AgNO₂ then HNO₂ + NaOH. 1° → red colour, 2° → blue colour, 3° → colourless (no colour change). Distinguishes all three classes.
13. Why is the C−O−C bond angle in ethers (~111°) greater than the H−O−H angle in water (104.5°)?
Explanation: In water, the two lone pairs compress the H−O−H angle to 104.5°. In ethers, the larger alkyl groups cause steric repulsion between them, which widens the C−O−C angle to ~111° (close to tetrahedral 109.5°).