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Write the chemical equation… (Class 12 Chemistry 2024, Q21)

questionbuddy.in/q/cbse-12-chemistry-2024-56-1-1-q21-chemical-equation-butan-treated-conc

ChemistryCBSE Class 12 · Board exam 2024, set 56/1/1 · 2 marks · Very short answer

CBSE Class 12 Chemistry 2024: question 21

Set in the CBSE Class 12 board exam of 2024, paper 56/1/1, section B, question 21, for 2 marks. Try it first; the hints and our step-by-step solution are below.

Q21 · 2 marks · Very short answerAldehydes, Ketones and Carboxylic Acids

Write the chemical equation when :
(a) Butan-2-one is treated with Zn(Hg) and conc. HCl.
(b) Two molecules of benzaldehyde are treated with conc. NaOH.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2024 board paper, set 56/1/1.

Hints

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

Hint 1

Zn(Hg)/conc. HCl is a named reduction of carbonyl compounds.

Hint 2

An aldehyde without α-hydrogen in conc. alkali disproportionates.

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. (a) Clemmensen reduction converts C=O to CH₂: (butane).

    1 mark

  2. (b) Cannizzaro reaction (benzaldehyde has no α-H): (benzyl alcohol + sodium benzoate).

    1 mark

Answer: (a) Butane; (b) Benzyl alcohol + sodium benzoate (Cannizzaro reaction)

Where the marks are

  • Clemmensen reduction equation giving butane (1 mark)
  • Cannizzaro equation giving benzyl alcohol and sodium benzoate (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 paper2024 board paper, set 56/1/1: 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.