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An organic compound with… (Class 12 Chemistry 2026, Q28b)

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ChemistryCBSE Class 12 · Board exam 2026, set 56/5/1 · 3 marks · Short answer

CBSE Class 12 Chemistry 2026: question 28(b)

Set in the CBSE Class 12 board exam of 2026, paper 56/5/1, section C, question 28(b), for 3 marks. Try it first; the hints and our step-by-step solution are below.

Q28(b) · 3 marks · Short answerAldehydes, Ketones and Carboxylic Acids

An organic compound with the molecular formula forms 2,4-DNP derivative, reduces Tollens’ reagent and undergoes Cannizzaro reaction. On vigorous oxidation it gives Benzene-1,2-dicarboxylic acid. Identify the compound and write the reactions of compound 2,4-DNP and when it undergoes Cannizzaro reaction.

Source: official question paper from cbse.gov.in (PDF). See it in the full 2026 board paper, set 56/5/1.

Hints

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

Hint 1

Tollens' test plus the Cannizzaro reaction points to an aldehyde with no α-hydrogen.

Hint 2

Benzene-1,2-dicarboxylic acid means two carbon substituents sit ortho to each other; fit C₈H₈O around that.

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. The compound forms a 2,4-DNP derivative, so it has C=O. It reduces Tollens' reagent, so it is an aldehyde. It undergoes the Cannizzaro reaction, so it has no α-H (–CHO on the ring). Vigorous oxidation gives benzene-1,2-dicarboxylic acid, so it has two substituents in ortho positions. With the compound is 2-methylbenzaldehyde (o-tolualdehyde), .

    On vigorous oxidation:

    1 mark

  2. With 2,4-DNP:

    The product is the orange-red 2,4-dinitrophenylhydrazone.

    1 mark

  3. Cannizzaro reaction:

    The products are 2-methylbenzyl alcohol and sodium 2-methylbenzoate.

    1 mark

Answer: 2-Methylbenzaldehyde (o-tolualdehyde); gives 2,4-DNP hydrazone; Cannizzaro gives 2-methylbenzyl alcohol + sodium 2-methylbenzoate

Where the marks are

  • Identifies 2-methylbenzaldehyde with reasoning (1 mark)
  • Correct 2,4-DNP derivative equation (1 mark)
  • Correct Cannizzaro equation (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 paper2026 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.