Important Questions Class 12 Chemistry Chapter 7 focus on the study of Alcohols, Phenols, and Ethers, which are fundamental organic compounds used in both industrial processes and everyday life. Understanding their preparation, properties, and reactions is crucial for scoring well in Class 12 Board exams and competitive entrance tests like NEET and JEE. Here, we break down the chapter into high-yield topics, including Williamson’s synthesis, acidity of phenols, and various nucleophilic substitution reactions, ensuring you have the most factually accurate data for your preparation. 

Important Questions Class 12 Chemistry Chapter 7 PDF

This resource provides a structured collection of high-yield questions, numerical problems, and conceptual explanations specifically for Chapter 7: Alcohols, Phenols, and Ethers. Derived from the Practice Sheet-01 (Chemistry for NEET-JEE), it covers essential topics including Williamson’s synthesis, the acidity of phenols, Reimer-Tiemann reactions, and the cleavage of ethers to help students prepare for Board examinations and competitive entrance tests.

Class 12 Chemistry Practice Sheet - Sandeep Sir & Rajinder

Alcohols, Phenols, and Ethers Class 12 Important Questions

The following questions highlight the core concepts frequently tested in examinations.

1. Question:
To synthesize tertiary butyl methyl ether, which of the following reagent sets is better?

(i) (CH3)3C–Br + CH3ONa
(ii) (CH3)3C–ONa + CH3–Br

Answer:
Set (ii) is the better choice. Williamson’s synthesis follows an SN2 mechanism. Using a primary halide (CH3–Br) with a bulky alkoxide prevents elimination, which would occur with a tertiary halide like (CH3)3C–Br.

2. Question:
How are the following conversions carried out? Represent them with chemical equations.

(a) Phenol to Benzene
(b) Phenol to Picric Acid
(c) Phenol to Tribromophenol

Answer:
(a) Phenol is heated with zinc dust to form benzene.
(b) Phenol reacts with concentrated HNO3 to form 2,4,6-trinitrophenol.
(c) Phenol reacts with bromine water to form 2,4,6-tribromophenol.

3. Question:
Can ethanol be prepared by treating HCHO with CH3CH2MgBr?

Answer:
No. Formaldehyde reacts with ethyl magnesium bromide to give propan-1-ol after hydrolysis. To prepare ethanol, formaldehyde must react with methyl magnesium bromide.

4. Question:
Explain the cleavage of the C–O bond in CH3–CH2–O–CH3 when treated with HI.

Answer:
The ether oxygen is first protonated. Then iodide ion attacks the methyl group by SN2 mechanism, producing CH3I and CH3CH2OH.

5. Question:
Write the chemical equation for the Reimer–Tiemann reaction.

Answer:
Phenol reacts with CHCl3 and NaOH followed by acidification to form ortho-hydroxybenzaldehyde (salicylaldehyde).

Class 12 Chemistry Alcohols, Phenols, and Ethers MCQ

The following questions highlight the core concepts frequently tested in examinations.

1. Which of the following is the most suitable for the synthesis of tertiary butyl methyl ether?

(1) $(CH_{3})_{3}C-Br + CH_{3}ONa$

(2) $(CH_{3})_{3}C-ONa + CH_{3}-Br$

(3) $CH_{3}OH + (CH_{3})_{3}C-OH / H^{+}$

(4) $(CH_{3})_{3}C-Cl + CH_{3}Cl / Na$

Answer: (2)

2. Formaldehyde reacts with methyl magnesium bromide followed by hydrolysis to yield:

(1) Methanol

(2) Ethanol

(3) Propan-1-ol

(4) Propan-2-ol

Answer: (2)

3. Phenol reacts with concentrated $HNO_{3}$ to produce:

(1) o-Nitrophenol

(2) p-Nitrophenol

(3) 2,4,6-Trinitrophenol

(4) Benzene

Answer: (3)

4. Reaction of phenol with bromine water gives a white precipitate of:

(1) 2-Bromophenol

(2) 4-Bromophenol

(3) 2,4,6-Tribromophenol

(4) Bromobenzene

Answer: (3)

5. The cleavage of $CH_{3}-CH_{2}-O-CH_{3}$ with cold $HI$ yields:

(1) $CH_{3}CH_{2}I$ and $CH_{3}OH$

(2) $CH_{3}I$ and $CH_{3}CH_{2}OH$

(3) $CH_{3}CH_{2}I$ and $CH_{3}I$

(4) Ethane and Methanol

Answer: (2)

6. Which alcohol reacts most rapidly with Lucas reagent?

(1) Butan-1-ol

(2) Butan-2-ol

(3) 2-Methylpropan-2-ol

(4) Ethanol

Answer: (3)

7. Reimer-Tiemann reaction introduces which group to the phenol ring?

(1) $-COOH$

(2) $-CHO$

(3) $-CH_{3}$

(4) $-NO_{2}$

Answer: (2)

8. Denaturation of alcohol involves adding poisonous substances like:

(1) Methanol

(2) Water

(3) Sugar

(4) Glucose

Answer: (1)

9. Heating ethanol with conc. $H_{2}SO_{4}$ at $443~K$ yields:

(1) Diethyl ether

(2) Ethene

(3) Ethanal

(4) Ethane

Answer: (2)

10. Which has the highest boiling point?

(1) Ethanol

(2) Propan-1-ol

(3) Butan-1-ol

(4) Butan-2-ol

Answer: (3)