ChemistryCBSE Class 12 · Board exam 2023, set 56/1/1 · 1 mark · MCQ

CBSE Class 12 Chemistry 2023: question 10

Set in the CBSE Class 12 board exam of 2023, paper 56/1/1, section A, question 10, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q10 · 1 mark · MCQAlcohols, Phenols and Ethers

In the reaction $R - OH + HCl ZnC l_{2} RCl + H_{2} O$ , what is the correct order of reactivity of alcohol ?

(A) $1^{\circ} < 2^{\circ} < 3^{\circ}$
(B) $1^{\circ} > 3^{\circ} > 2^{\circ}$
(C) $1^{\circ} > 2^{\circ} > 3^{\circ}$
(D) $3^{\circ} > 1^{\circ} > 2^{\circ}$

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 56/1/1.

Hints

Open one hint at a time and try again before the next.

Hint 1

This is the Lucas test.

Hint 2

Which alcohol gives turbidity immediately?

Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

With Lucas reagent the reaction goes through a carbocation, and carbocation stability is $3^{\circ} > 2^{\circ} > 1^{\circ}$ .
So the reactivity order is $1^{\circ} < 2^{\circ} < 3^{\circ}$ . Option (A).
1 mark

Answer: $1^{\circ} < 2^{\circ} < 3^{\circ}$ , option (A)

Where the marks are

Correct order based on carbocation stability (1 mark)

Revise the chapter

Chapter: Alcohols, Phenols and Ethers (notes, formulas, where marks are lost and every past question)

Practise this chapterBoard-style questions from Alcohols, Phenols and Ethers, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 56/1/1: every question, by section.

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CBSE Class 12 Chemistry 2023: question 10

Hints

Step-by-step solution

Revise the chapter

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