CBSE Class 12 Alcohols, Phenols and Ethers PYQs Analysis (2021-2025)

Based on detailed analysis of last 5 years' papers. Perfect for 2026 Boards prep!

Key Trends

Weightage Breakdown: 1-2 MCQs/assertion-reason (1 mark), 1 short answer (2 marks), 1 reaction-based (3 marks), occasional case-based (4 marks).
Repeated Topics: Lucas test, Reimer-Tiemann, Kolbe's reaction, acidity comparison, Williamson synthesis, ether cleavage.
Difficulty: Medium; mechanisms and conversions key.
Changes: More on mechanisms in later years.

Most Important and Repeated Questions

Question Example	Type/Marks	Years Repeated	Notes
Why is phenol more acidic than ethanol? Explain with resonance structures of phenoxide ion.	Reasoning (2 marks)	2022, 2023, 2024, 2025	Repeated 4x; Resonance delocalizes charge in phenoxide.
Describe Lucas test to distinguish 1°, 2°, 3° alcohols. What is the order of reactivity?	Short Answer (2 marks)	2021 Term 2, 2022, 2023, 2025	Repeated 4x; Conc HCl + ZnCl2; 3° > 2° > 1°.
What is Reimer-Tiemann reaction? Give equation for phenol to salicylaldehyde. Why ortho major?	Reaction (3 marks)	2021 Term 1, 2023, 2024, 2025	Repeated 4x; Phenol + CHCl3 + aq NaOH → o-HO-C6H4-CHO.
What is Kolbe's reaction? Give equation for preparation of salicylic acid from phenol.	Short Answer (2 marks)	2022, 2024	Repeated 2x; Phenol + NaOH → sodium phenoxide + CO2 → salicylic acid.
Assertion: Ethers are cleaved by hot conc HI. Reason: I⁻ attacks less hindered carbon.	Assertion-Reason (1 mark)	2023, 2024, 2025	Repeated 3x; SN2/SN1 mechanism.
Convert ethanol to ethoxyethane (Williamson synthesis equation). Why unsymmetrical ethers use alkoxide of 1°?	Conversion (2 marks)	2021 Term 2, 2022, 2024	Repeated 3x; CH3CH2ONa + CH3CH2Br → CH3CH2OCH2CH3.
Why phenols do not give Lucas test? Distinguish phenol from alcohol (neutral FeCl3 test).	Reasoning (2 marks)	2023, 2025	Repeated 2x; Phenol acidic, violet with FeCl3.
MCQ: Product of Reimer-Tiemann with chloroform on phenol: (a) Benzaldehyde (b) Salicylaldehyde.	MCQ (1 mark)	2024, 2025	Repeated 2x; (b) o-hydroxybenzaldehyde.
Case-based: Dehydration of alcohols to alkenes/ethers. Give conditions for 1° vs 3° alcohols.	Case-Based (4 marks)	2022, 2025	Repeated 2x; 1° high temp ether, 3° room temp alkene.
Compare boiling points: Ethanol vs dimethyl ether vs phenol (H-bonding).	Short Answer (2 marks)	2021 Term 1, 2023	Repeated 2x; Phenol > ethanol > ether.

Best Format for Preparation and Answering

Study Format: Tables for reactions (reagents, products, conditions), flowcharts for conversions. Practice 10 PYQs on tests/mechanisms.
Answer Format: Reactions: Equation + conditions + mechanism if asked. Reasoning: Factor (resonance/H-bond) + comparison.
Tips: Focus on phenol reactions (high marks). Time: 8 mins.

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