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Assertion (A) : Trans [Cr… (Class 12 Chemistry 2023, Q18)

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

CBSE Class 12 Chemistry 2023: question 18

Set in the CBSE Class 12 board exam of 2023, paper 56/5/1, section A, question 18, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q18 · 1 mark · Assertion-reasonCompetency-basedCoordination Compounds

Assertion (A) : Trans shows optical isomerism.
Reason (R) : Optical isomerism is common in octahedral complexes involving didentate ligands.

  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

Look for a plane of symmetry in the trans isomer.

Hint 2

Which isomer, cis or trans, is chiral?

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 trans isomer has a mirror plane containing the two ox ligands, so it is achiral. The Assertion is false.

  2. Octahedral complexes with didentate ligands (for example cis isomers) commonly show optical isomerism, so the Reason is true.

    1 mark

Answer: (D)

Where the marks are

  • States A is false and R is true (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from Coordination Compounds, 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.