Atoms MCQs Class 12 Physics (Bohr Model)
Atoms MCQs – Bohr Model
Class: CBSE Class 12
Subject: Physics
Section: Atoms and Nuclei
Topic: Bohr Model of Atom
Based on: CBSE Board Examination Pattern (NCERT)
Instructions: These Multiple Choice Questions (MCQs) are designed strictly as per the NCERT syllabus, making them ideal for CBSE Class 12 Board Examination preparation.
1. Bohr model explains spectrum of:
Answer: A
Bohr theory is valid mainly for hydrogen-like atoms.
Bohr theory is valid mainly for hydrogen-like atoms.
2. Electron revolves in:
Answer: B
Bohr assumed fixed circular stationary orbits.
Bohr assumed fixed circular stationary orbits.
3. Angular momentum is quantized as:
Answer: A
L = nħ = nh/2π.
L = nħ = nh/2π.
4. Energy levels in atom are:
Answer: B
Electrons occupy quantized energy states.
Electrons occupy quantized energy states.
5. Radius of orbit depends on:
Answer: A
rₙ ∝ n².
rₙ ∝ n².
6. Ground state corresponds to:
Answer: B
Lowest energy level.
Lowest energy level.
7. Energy of nth orbit ∝
Answer: A
Energy decreases with n².
Energy decreases with n².
8. Ionization energy is energy required to:
Answer: B
Electron taken to n = ∞.
Electron taken to n = ∞.
9. Spectral lines are due to:
Answer: B
Photon emitted during transitions.
Photon emitted during transitions.
10. Rydberg constant relates to:
Answer: A
Used in hydrogen spectrum formula.
Used in hydrogen spectrum formula.
11. Lyman series lies in:
Answer: A
Transitions to n = 1.
Transitions to n = 1.
12. Balmer series lies in:
Answer: A
Transitions to n = 2.
Transitions to n = 2.
13. Paschen series lies in:
Answer: A
Transitions to n = 3.
Transitions to n = 3.
14. Electron energy is negative because:
Answer: A
Energy required to free electron.
Energy required to free electron.
15. Highest energy orbit:
Answer: C
Electron free from nucleus.
Electron free from nucleus.
16. Frequency of emitted photon depends on:
Answer: A
ΔE = hν.
ΔE = hν.
17. Bohr radius is about:
Answer: A
Radius of first orbit.
Radius of first orbit.
18. Excited state means:
Answer: A
Electron in n ≥ 2.
Electron in n ≥ 2.
19. Spectrum is:
Answer: B
Discrete wavelengths.
Discrete wavelengths.
20. Bohr model limitation:
Answer: A
Fails for complex atoms.
Fails for complex atoms.
