Structure of Atom NEET Previous Year Questions (PYQs)
Practice NEET previous year questions from Structure of Atom. These MCQs cover quantum numbers, Bohr model, electronic configuration, spectra, de Broglie wavelength and uncertainty principle with answers and clear explanations.
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Structure of Atom Chapter Notes
Q1. Which one is a wrong statement?
(NEET 2018)
- (A) Total orbital angular momentum of electron in s-orbital is zero
- (B) An orbital is designated by three quantum numbers
- (C) The electronic configuration of nitrogen is incorrect
- (D) The value of magnetic quantum number for dz² is zero
Show Answer
(C)
Show Explanation
Correct electronic configuration of nitrogen is 1s² 2s² 2p³. Option (C) is incorrect.
Q2. Which one is the wrong statement?
(NEET 2017)
- (A) Uncertainty principle is Δx·Δp ≥ h/4π
- (B) Half-filled orbitals are more stable
- (C) Energy of 2s is less than 2p in hydrogen-like atoms
- (D) de Broglie wavelength λ = h/mv
Show Answer
(C)
Show Explanation
In hydrogen-like atoms, energy depends only on n. Hence 2s and 2p have equal energy.
Q3. Two electrons occupying the same orbital are distinguished by:
(NEET 2016)
- (A) Principal quantum number
- (B) Azimuthal quantum number
- (C) Magnetic quantum number
- (D) Spin quantum number
Show Answer
(D)
Show Explanation
Pauli’s exclusion principle states electrons in same orbital differ in spin.
Q4. Correct order of increasing energy of orbitals in Ti (Z = 22) is:
(NEET 2015)
- (A) 3s < 4s < 3p < 3d
- (B) 4s < 3s < 3p < 3d
- (C) 3s < 3p < 3d < 4s
- (D) 3s < 3p < 4s < 3d
Show Answer
(D)
Show Explanation
Based on (n+l) rule, energy order is 3s < 3p < 4s < 3d.
Q5. Angular momentum of electron in d-orbital is:
(NEET 2015)
- (A) √2 h/2π
- (B) √6 h/2π
- (C) 0
- (D) √6 ħ
Show Answer
(D)
Show Explanation
Angular momentum = √l(l+1)ħ. For d-orbital, l = 2 → √6 ħ.
Q6. Maximum number of orbitals for n = 3, l = 1, m = 0 is:
(NEET 2014)
- (A) 1
- (B) 2
- (C) 3
- (D) 4
Show Answer
(A)
Show Explanation
For a given value of m, only one orbital exists.
Q7. Be²⁺ is isoelectronic with:
(NEET 2014)
- (A) H⁺
- (B) Li⁺
- (C) Na⁺
- (D) Mg²⁺
Show Answer
(B)
Show Explanation
Be²⁺ has 2 electrons, same as Li⁺.
Q8. Series of hydrogen spectrum lying in visible region is:
(NEET 2019)
- (A) Lyman
- (B) Balmer
- (C) Paschen
- (D) Brackett
Show Answer
(B)
Show Explanation
Balmer series corresponds to visible region.
Q9. Orbital with 3 angular nodes and 3 total nodes is:
(NEET 2019)
- (A) 5p
- (B) 3d
- (C) 4f
- (D) 6d
Show Answer
(C)
Show Explanation
Angular nodes = l = 3, radial nodes = n − l − 1 = 0 → total = 3.
Q10. Number of angular and radial nodes in 3s orbital are:
(NEET 2020)
- (A) 0 and 2
- (B) 1 and 0
- (C) 3 and 0
- (D) 0 and 1
Show Answer
(A)
Show Explanation
For s-orbital, l = 0 → angular nodes = 0; radial nodes = n − 1 = 2.
Q11. Longest wavelength in Balmer series is:
(NEET 1996)
- (A) 546 nm
- (B) 656 nm
- (C) 566 nm
- (D) 556 nm
Show Answer
(B)
Show Explanation
Transition n = 3 → 2 gives maximum wavelength (lowest energy).
Q12. Orientation of an atomic orbital is governed by:
(NEET 2006)
- (A) Principal quantum number
- (B) Azimuthal quantum number
- (C) Magnetic quantum number
- (D) Spin quantum number
Show Answer
(C)
Show Explanation
Magnetic quantum number (m) decides orbital orientation.
Q13. Maximum number of electrons in f-subshell is:
(NEET 1991)
- (A) 10
- (B) 12
- (C) 14
- (D) 16
Show Answer
(C)
Show Explanation
f-subshell has 7 orbitals × 2 electrons = 14.
Q14. Principle stating no two electrons can have same four quantum numbers is:
(NEET 1991)
- (A) Hund’s rule
- (B) Aufbau principle
- (C) Pauli exclusion principle
- (D) Uncertainty principle
Show Answer
(C)
Show Explanation
This is Pauli’s exclusion principle.
Q15. The number of atomic orbitals in fourth energy level is:
(NEET 2011)
- (A) 4
- (B) 8
- (C) 16
- (D) 32
Show Answer
(C)
Show Explanation
Total orbitals in nth shell = n² = 16.
Q16. Modified Bohr’s model introducing elliptical orbits was proposed by:
(NEET 1999)
- (A) Rutherford
- (B) Thomson
- (C) Hund
- (D) Sommerfeld
Show Answer
(D)
Show Explanation
Sommerfeld introduced elliptical orbits.
Q17. Isoelectronic species have:
(NEET 2000)
- (A) Same atomic number
- (B) Same number of electrons
- (C) Same mass
- (D) Same charge
Show Answer
(B)
Show Explanation
Isoelectronic species possess equal number of electrons.
Q18. The uncertainty principle states:
(NEET 1989)
- (A) Δx·Δp ≥ h/4π
- (B) Δx = Δp
- (C) Energy is quantised
- (D) Orbitals are elliptical
Show Answer
(A)
Show Explanation
Heisenberg uncertainty principle gives this relation.
Q19. Electronic configuration of Cu (Z = 29) is:
(NEET 1991)
- (A) [Ar] 3d⁹ 4s²
- (B) [Ar] 3d¹⁰ 4s¹
- (C) [Ar] 3d⁸ 4s³
- (D) [Kr] 4d¹⁰
Show Answer
(B)
Show Explanation
Cu shows exceptional stability with half-filled 4s and filled 3d.
Q20. Longest wavelength corresponds to transition:
(NEET 1996)
- (A) n = 2 → 1
- (B) n = 3 → 2
- (C) n = 4 → 2
- (D) n = 5 → 2
Show Answer
(B)
Show Explanation
Smallest energy gap gives longest wavelength.
👉 More Structure of Atom NEET PYQs will be added gradually.