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Atomic Structure JEE Main MCQ & Practice Questions

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

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Atomic Structure Revision Guide for JEE Main Chemistry

Atomic Structure provides the foundation for electronic configuration, periodic trends and chemical bonding. Strong preparation requires understanding the quantum description of electrons rather than memorising isolated rules.

For JEE Main Chemistry, revise electromagnetic radiation, the Bohr model, de Broglie relation, uncertainty principle, quantum numbers, orbital shapes and electronic configuration.

Important Topics

  • Electromagnetic radiation and photons
  • Bohr model and hydrogen spectrum
  • de Broglie wavelength
  • Heisenberg uncertainty principle
  • Quantum numbers and orbitals
  • Electronic configuration and stability

Important Formulae & Relationships

  • E = hν
  • c = λν
  • λ = h/mv
  • En = −13.6 Z²/n² eV (hydrogen-like species)
  • 1/λ = RZ²(1/n1² − 1/n2²)

Use formulas only after checking the required units, sign convention and assumptions for the question.

What to practise in Atomic Structure

Concept Revision

Revise definitions, principles, equations, trends and core ideas from Atomic Structure before attempting MCQs.

Exam-style MCQs

Use chapter-focused multiple-choice practice to improve accuracy, recall and application for JEE Main Chemistry.

Performance Practice

Attempt ChemNexa tests, review results and return to weak areas for another round of targeted revision.

Top 20 Atomic Structure MCQs with Answers

These public questions are selected from the exact Atomic Structure 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 · Atomic Structure · Very Very Hard

1. Heisenberg uncertainty principle is represented by

  • A. ΔxΔp ≥ h/4π
  • B. ΔxΔp=0
  • C. ΔxΔp=h^2
  • D. Δx=Δp
Answer: A
Explanation: Position and momentum cannot both be known with arbitrary precision.

JEE Main Chemistry · Atomic Structure · Very Very Hard

2. The number of orbitals in a shell with principal quantum number n is

  • A. 2n^2
  • B. n
  • C. 2n
  • D. n^2
Answer: D
Explanation: A shell contains n^2 orbitals.

JEE Main Chemistry · Atomic Structure · Very Very Hard

3. Total number of nodes in an orbital is

  • A. 2n
  • B. n-1
  • C. n
  • D. l+1
Answer: B
Explanation: Total nodes=radial+angular=n-l-1+l=n-1.

JEE Main Chemistry · Atomic Structure · Very Very Hard

4. Number of angular nodes is

  • A. l
  • B. n-l-1
  • C. n-1
  • D. 2l+1
Answer: A
Explanation: Angular nodes equal the azimuthal quantum number.

JEE Main Chemistry · Atomic Structure · Very Very Hard

5. For a 3p orbital, total nodes and angular nodes respectively are

  • A. 2 and 2
  • B. 1 and 2
  • C. 2 and 1
  • D. 3 and 1
Answer: C
Explanation: Total nodes=3-1=2; angular nodes=l=1.

JEE Main Chemistry · Atomic Structure · Very Very Hard

6. For a 4s orbital, number of radial nodes is

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

JEE Main Chemistry · Atomic Structure · Very Very Hard

7. Aufbau principle states electrons occupy

  • A. Lower-energy orbitals before higher-energy orbitals
  • B. Higher-energy orbitals first
  • C. Only degenerate orbitals
  • D. Orbitals randomly
Answer: A
Explanation: Ground states are built by filling lower-energy orbitals first.

JEE Main Chemistry · Atomic Structure · Very Very Hard

8. Pauli exclusion principle permits a maximum of how many electrons in one orbital?

  • A. 1
  • B. 3
  • C. 4
  • D. 2
Answer: D
Explanation: Two electrons may occupy an orbital with opposite spins.

JEE Main Chemistry · Atomic Structure · Very Very Hard

9. Hund's rule states electrons occupy degenerate orbitals

  • A. With opposite spins singly
  • B. Only after s orbitals are empty
  • C. Singly with parallel spins before pairing
  • D. In pairs immediately
Answer: C
Explanation: Maximum multiplicity is favoured.

JEE Main Chemistry · Atomic Structure · Very Very Hard

10. Which orbital has no radial node?

  • A. 2s
  • B. 3s
  • C. 3p
  • D. 2p
Answer: D
Explanation: For 2p, n-l-1=2-1-1=0.

JEE Main Chemistry · Atomic Structure · Very Very Hard

11. JEE Main advanced

  • A. n-1
  • B. 2l+1
  • C. l
  • D. n-l-1
Answer: C
Explanation: Angular nodes equal the azimuthal quantum number.

JEE Main Chemistry · Atomic Structure · Very Very Hard

12. Bohr quantised angular momentum as

  • A. mvr = 2πnh
  • B. mvr = nh/2π
  • C. mvr = nh
  • D. mvr = h/4π
Answer: B
Explanation: Bohr's postulate gives mvr=nh/2π.

JEE Main Chemistry · Atomic Structure · Very Very Hard

13. For a hydrogen-like species, the radius of the nth Bohr orbit varies as

  • A. n^2/Z
  • B. Z/n^2
  • C. n/Z^2
  • D. Zn^2
Answer: A
Explanation: r_n is proportional to n^2/Z.

JEE Main Chemistry · Atomic Structure · Very Very Hard

14. The de Broglie wavelength of a particle is

  • A. λ=p/h
  • B. λ=hE
  • C. λ=h/p
  • D. λ=hp
Answer: C
Explanation: Matter-wave wavelength is inversely proportional to momentum.

JEE Main Chemistry · Atomic Structure · Very Very Hard

15. If momentum of a particle doubles, its de Broglie wavelength becomes

  • A. Unchanged
  • B. Half
  • C. Double
  • D. Four times
Answer: B
Explanation: λ=h/p.

JEE Main Chemistry · Atomic Structure · Very Very Hard

16. The square of a wavefunction, |ψ|^2, represents

  • A. Electron charge
  • B. Orbital energy only
  • C. Nuclear density
  • D. Probability density
Answer: D
Explanation: Born interpretation associates |ψ|^2 with probability density.

JEE Main Chemistry · Atomic Structure · Very Very Hard

17. An atomic orbital is best described as

  • A. A proton path
  • B. A classical trajectory
  • C. A wavefunction/probability distribution
  • D. A fixed circular path
Answer: C
Explanation: Orbitals are quantum-mechanical states, not classical orbits.

JEE Main Chemistry · Atomic Structure · Very Very Hard

18. The principal quantum number primarily determines

  • A. Only orbital shape
  • B. Shell and approximate size/energy
  • C. Orbital orientation
  • D. Electron spin
Answer: B
Explanation: n identifies the principal shell.

JEE Main Chemistry · Atomic Structure · Very Very Hard

19. For a d subshell, number of orbitals is

  • A. 7
  • B. 1
  • C. 5
  • D. 3
Answer: C
Explanation: m_l values -2,-1,0,+1,+2 give five orbitals.

JEE Main Chemistry · Atomic Structure · Very Very Hard

20. For an f subshell, number of orbitals is

  • A. 9
  • B. 7
  • C. 5
  • D. 3
Answer: B
Explanation: 2l+1=7 when l=3.

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Atomic Structure Practice Tests

Atomic Structure Frequently Asked Questions

Which Atomic Structure topics are most connected to later chapters?

Quantum numbers, orbitals and electronic configuration directly support periodicity, chemical bonding and coordination chemistry.

How should I learn quantum numbers?

Connect each quantum number with what it describes: shell, subshell, orbital orientation and electron spin. Then practise allowed and forbidden combinations.

Are formula-based questions enough for Atomic Structure?

No. Exams also test conceptual interpretation of spectra, orbitals, nodes, electronic configurations and quantum-number restrictions.

Continue with another chapter to build connected concepts and strengthen your overall Chemistry preparation.

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