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Assertion (A) : Acetic acid… (Class 12 Chemistry 2023, Q17)

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ChemistryCBSE Class 12 · Board exam 2023, set 56/5/1 · 1 mark · Assertion-reason

CBSE Class 12 Chemistry 2023: question 17

Set in the CBSE Class 12 board exam of 2023, paper 56/5/1, section A, question 17, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q17 · 1 mark · Assertion-reasonCompetency-basedAldehydes, Ketones and Carboxylic Acids

Assertion (A) : Acetic acid but not formic acid can be halogenated in presence of red P and .
Reason (R) : Acetic acid is a weaker acid than formic acid.

  1. (A)Both Assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of the Assertion (A).
  2. (B)Both Assertion (A) and Reason (R) are true, but Reason (R) is not the correct explanation of the Assertion (A).
  3. (C)Assertion (A) is true, but Reason (R) is false.
  4. (D)Assertion (A) is false, but Reason (R) is true.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2023 board paper, set 56/5/1.

Hints

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

Hint 1

Which structural feature does the HVZ reaction require?

Hint 2

Is acid strength related to that requirement?

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.

  1. HVZ halogenation needs an α-hydrogen. Acetic acid has α-hydrogens, but formic acid has none, so the Assertion is true.

  2. Acetic acid is indeed weaker than formic acid (because of the +I effect of ), so the Reason is true. However, this is not why HVZ halogenation occurs.

    1 mark

Answer: (B)

Where the marks are

  • States both are true and R is not the correct explanation (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Aldehydes, Ketones and Carboxylic Acids, one at a time, marked against the answer key and marking points.Back to the full paper2023 board paper, set 56/5/1: every question, by section.

The question is transcribed from the official paper; figures are described in words. The solution, hints and chapter tag are ours. Spotted an error? Write tosupport@questionbuddy.in.