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Out of the four options… (Class 12 Physics 2025, Q10)

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PhysicsCBSE Class 12 · Board exam 2025, set 55/7/1 · 1 mark · MCQ

CBSE Class 12 Physics 2025: question 10

Set in the CBSE Class 12 board exam of 2025, paper 55/7/1, section A, question 10, for 1 mark. Try it first; the hints and our step-by-step solution are below.

Q10 · 1 mark · MCQAtoms

Out of the four options given, in which transition will the emitted photon have the maximum wavelength ?

  1. (A)n = 4 to n = 3
  2. (B)n = 3 to n = 2
  3. (C)n = 2 to n = 1
  4. (D)n = 3 to n = 1

Source: official question paper from cbse.gov.in (PDF). See it in the full 2025 board paper, set 55/7/1.

Hints

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

Hint 1

How are wavelength and energy of a photon related?

Hint 2

Energy levels get closer together for higher n.

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. , so the maximum wavelength comes from the minimum energy gap.

    ½ mark

  2. for n = 4 → 3 is eV, the smallest of the four options.

    ½ mark

Answer: n = 4 to n = 3, option (A)

Where the marks are

  • Links maximum λ to minimum ΔE (1 mark)

Revise the chapter

  • Chapter: Atoms (notes, formulas, where marks are lost and every past question)
Practise this chapterBoard-style questions from Atoms, one at a time, marked against the answer key and marking points.Back to the full paper2025 board paper, set 55/7/1: 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.