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Assertion (A) : Highest… (Class 12 Chemistry 2026, Q14)

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ChemistryCBSE Class 12 · Board exam 2026, set 56/5/1 · 1 mark · Assertion-reason

CBSE Class 12 Chemistry 2026: question 14

Set in the CBSE Class 12 board exam of 2026, paper 56/5/1, section A, question 14, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q14 · 1 mark · Assertion-reasonCompetency-basedThe d- and f-Block Elements

Assertion (A) : Highest oxidation state of Mn is +7 in first series of transition elements.
Reason (R) : Transition metals exhibit variable oxidation states.

  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 2026 board paper, set 56/5/1.

Hints

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

Hint 1

Write the electronic configuration of Mn.

Hint 2

Check whether R gives the specific reason for +7.

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. Mn shows +7 (as in ), the highest oxidation state in the 3d series, so A is true. Transition metals do show variable oxidation states, so R is true.

  2. However, R is only a general fact and does not explain why Mn reaches +7. That is due to the use of all its 4s and 3d electrons (). Option (B).

    1 mark

Answer: (B)

Where the marks are

  • Both true, R not the explanation (1 mark)

Revise the chapter

Practise this chapterBoard-style questions from The d- and f-Block Elements, 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.