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Structure of Atom JEE Main MCQ & Practice Questions

Practice Structure of Atom MCQs for JEE Main Chemistry with answers, explanations, chapter revision and related ChemNexa mock tests.

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Structure of Atom Revision Guide for JEE Main Chemistry

Structure of Atom is part of JEE Main Chemistry preparation. A strong revision plan should combine concept review with exam-style questions so that definitions, relationships, calculations and exceptions are recalled accurately.

Use the sample MCQs on this page to check understanding, then attempt the related ChemNexa tests for broader practice. When an answer is wrong, review the explanation and return to the underlying concept before attempting another set.

Important Topics

  • Core definitions and principles
  • Important equations or relationships
  • Common applications and examples
  • Frequently confused concepts
  • Exam-style multiple-choice questions
  • Error review and targeted revision

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Create a one-page summary of trends, structures, reactions, exceptions and key terminology for Structure of Atom, then test recall with mixed MCQs.

What to practise in Structure of Atom

Concept Revision

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Exam-style MCQs

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Top 20 Structure of Atom MCQs with Answers

These public questions are selected from the exact Structure of Atom chapter, screened for topic relevance and deduplicated so repeated versions of the same MCQ are not shown publicly. Use them for quick revision, then sign in to attempt the complete test experience with more questions, results and performance review.

JEE Main Chemistry · Structure of Atom · Very Hard

1. An electron accelerated through 160 V has de Broglie wavelength closest to:

  • A. 0.049 Å
  • B. 10.309 Å
  • C. 0.097 Å
  • D. 0.194 Å
Answer: C
Explanation: For an electron, λ(Å) = 12.27/√V = 12.27/√(160) = 0.097 Å.

JEE Main Chemistry · Structure of Atom · Very Hard

2. Which statement correctly describes the photoelectric effect?

  • A. Stopping potential is independent of frequency
  • B. Photoelectron kinetic energy depends on frequency, not intensity
  • C. Kinetic energy depends only on intensity
  • D. Emission occurs below threshold frequency
Answer: B
Explanation: Einstein's equation Kmax = hν − φ shows that kinetic energy depends on frequency; intensity mainly affects the number of emitted electrons.

JEE Main Chemistry · Structure of Atom · Very Hard

3. If incident frequency is 1.1 times the threshold frequency ν0, the maximum kinetic energy of a photoelectron is:

  • A. 0.1hν0
  • B. 1.1hν0
  • C. hν0
  • D. 0
Answer: A
Explanation: Kmax = h(ν−ν0) = h(1.1ν0−ν0) = 0.1hν0.

JEE Main Chemistry · Structure of Atom · Very Hard

4. According to Heisenberg's uncertainty principle:

  • A. ΔxΔp = 0
  • B. ΔxΔv ≥ h
  • C. Position and momentum can both be exact
  • D. ΔxΔp ≥ h/4π
Answer: D
Explanation: The minimum product of position and momentum uncertainties is h/4π.

JEE Main Chemistry · Structure of Atom · Very Hard

5. For a hydrogen-like ion with atomic number Z=3, the energy of the n=3 orbit is proportional to:

  • A. +9/3
  • B. −9/9
  • C. −9/9
  • D. −3/3
Answer: C
Explanation: For hydrogen-like species, En ∝ −Z²/n².

JEE Main Chemistry · Structure of Atom · Very Hard

6. For a hydrogen-like species with Z=2, the radius of the n=3 orbit in units of a0 is:

  • A. 18.00
  • B. 4.50
  • C. 1.50
  • D. 0.22
Answer: B
Explanation: rn = a0 n²/Z = a0×9/2 = 4.50a0.

JEE Main Chemistry · Structure of Atom · Very Hard

7. The angular momentum of an electron in the nth Bohr orbit is:

  • A. nh/2π
  • B. h/2πn
  • C. n²h/2π
  • D. Zero
Answer: A
Explanation: Bohr quantisation gives mvr = nh/2π.

JEE Main Chemistry · Structure of Atom · Very Hard

8. The wavelength emitted when an electron in hydrogen falls from n=5 to n=2 is closest to:

  • A. 217.0 nm
  • B. 868.2 nm
  • C. 4.3 nm
  • D. 434.1 nm
Answer: D
Explanation: 1/λ = R(1/2²−1/5²), giving λ ≈ 434.1 nm.

JEE Main Chemistry · Structure of Atom · Very Hard

9. The Balmer series corresponds to transitions ending at:

  • A. n=3
  • B. n=4
  • C. n=2
  • D. n=1
Answer: C
Explanation: All Balmer lines terminate at n=2 and lie mainly in the visible region.

JEE Main Chemistry · Structure of Atom · Very Hard

10. The Lyman series lies mainly in the:

  • A. Microwave region
  • B. Ultraviolet region
  • C. Visible region
  • D. Infrared region
Answer: B
Explanation: Lyman transitions end at n=1 and have high photon energies in the ultraviolet.

JEE Main Chemistry · Structure of Atom · Very Hard

11. The maximum number of spectral lines produced when an electron de-excites from n=6 is:

  • A. 15
  • B. 6
  • C. 21
  • D. 10
Answer: A
Explanation: Maximum lines = n(n−1)/2 = 6×5/2 = 15.

JEE Main Chemistry · Structure of Atom · Very Hard

12. For n=4, the total number of orbitals in the shell is:

  • A. 8
  • B. 4
  • C. 32
  • D. 16
Answer: D
Explanation: A shell with principal quantum number n contains n² orbitals; 4² = 16.

JEE Main Chemistry · Structure of Atom · Very Hard

13. For n=4, the maximum number of electrons in the shell is:

  • A. 8
  • B. 18
  • C. 32
  • D. 16
Answer: C
Explanation: Maximum electrons in a shell = 2n² = 2×4² = 32.

JEE Main Chemistry · Structure of Atom · Very Hard

14. For l=2, the possible magnetic quantum numbers are:

  • A. −3 to +3
  • B. −2, −1, 0, +1, +2
  • C. −1, 0, +1
  • D. 0, +1, +2
Answer: B
Explanation: ml ranges from −l to +l in integral steps; for l=2 there are five values.

JEE Main Chemistry · Structure of Atom · Very Hard

15. Which set of quantum numbers is not allowed?

  • A. n=2, l=2, ml=0, ms=+1/2
  • B. n=3, l=2, ml=−1, ms=−1/2
  • C. n=1, l=0, ml=0, ms=+1/2
  • D. n=4, l=3, ml=+3, ms=−1/2
Answer: A
Explanation: For n=2, l can only be 0 or 1; l=2 is forbidden.

JEE Main Chemistry · Structure of Atom · Very Hard

16. The number of radial nodes in a 4p orbital is:

  • A. 1
  • B. 3
  • C. 0
  • D. 2
Answer: D
Explanation: Radial nodes = n−l−1 = 4−1−1 = 2.

JEE Main Chemistry · Structure of Atom · Very Hard

17. The number of angular nodes in a 4d orbital is:

  • A. 3
  • B. 0
  • C. 2
  • D. 1
Answer: C
Explanation: Angular nodes equal l; for a d orbital l=2.

JEE Main Chemistry · Structure of Atom · Very Hard

18. The total number of nodes in a 5f orbital is:

  • A. 5
  • B. 4
  • C. 3
  • D. 1
Answer: B
Explanation: Total nodes = n−1 = 5−1 = 4.

JEE Main Chemistry · Structure of Atom · Very Hard

19. Which orbital has zero probability density at the nucleus?

  • A. 2p
  • B. 1s
  • C. 2s
  • D. 3s
Answer: A
Explanation: Only s orbitals have nonzero electron density at the nucleus; p orbitals vanish at r=0.

JEE Main Chemistry · Structure of Atom · Very Hard

20. The correct order of penetration is:

  • A. f > d > p > s
  • B. p > s > d > f
  • C. s > d > p > f
  • D. s > p > d > f
Answer: D
Explanation: For a given shell, penetration decreases in the order s > p > d > f.

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Structure of Atom Practice Tests

Structure of Atom Frequently Asked Questions

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