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Which of the… (Class 12 Chemistry SQP 2025-26, Q1)

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ChemistryCBSE Class 12 · Sample paper, session 2025-26 · 1 mark · MCQ

CBSE Class 12 Chemistry sample paper 2025-26: question 1

From the official CBSE sample question paper for 2025-26, section A, question 1, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q1 · 1 mark · MCQAldehydes, Ketones and Carboxylic Acids

Which of the following reaction will lead to formation of ethyl methyl ketone:

  1. (A)heating with acidified
  2. (B)passing over heated copper
  3. (C)ozonolysis of
  4. (D)acetylene on reaction with

Source: official sample paper from cbseacademic.nic.in (PDF). See it in the full Sample paper 2025-26.

Hints

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

Hint 1

Ethyl methyl ketone is .

Hint 2

Ozonolysis splits a C=C into two C=O groups; check which fragment carries an ethyl and a methyl group.

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. Ozonolysis cleaves the C=C: . The ketone formed is butan-2-one (ethyl methyl ketone).

    1 mark

  2. (A) gives an aldehyde/acid, (B) a 2° alcohol over Cu gives acetone, (D) acetylene gives acetaldehyde, so only (C) is correct.

Answer: Option (C)

Where the marks are

  • Identifies ozonolysis giving butan-2-one (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 paperSample paper 2025-26: 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.