Structure of AtomNEET MCQs with solutions
Structure of Atom covers atomic models (Thomson, Rutherford, Bohr), quantum numbers, electronic configuration, Aufbau principle, Pauli's exclusion and Hund's rule. NEET tests Bohr model calculations (radius, energy, velocity), quantum number sets and electron configuration of elements and ions.
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- 11 Chemistry
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Q1Electronic Configuration of Atoms
According to the Aufbau principle, electrons fill orbitals in order of
Not quite — the answer is A.
Electrons occupy orbitals starting from lowest available energy upward; this building-up sequence is the core of the Aufbau principle. Option B reverses the order entirely. Options C and D (atomic number/mass) are irrelevant to orbital filling order.
Q2Electronic Configuration of Atoms
According to the (n+l) rule, an orbital with a lower (n+l) value has
Not quite — the answer is B.
A lower (n+l) value indicates lower energy, so that orbital is filled first per the Aufbau principle. Option A inverts both energy and filling order. Option D confuses penetration with the (n+l) rule.
Q3Quantum Numbers
How many quantum numbers are needed to completely describe an electron in an atom?
Not quite — the answer is C.
Four quantum numbers (n, l, ml, ms) are required to completely specify the state of an electron. Each addresses a different property: size, shape, orientation, and spin.
Q4Quantum Numbers
The principal quantum number n primarily determines which property of an orbital?
Not quite — the answer is B.
The principal quantum number n determines the size of the orbital and its energy level, and corresponds to the shell number. Shape is determined by l, orientation by ml.
Q5Important PYQ Mixed Concepts
The maximum number of electrons that can have l = 2 in an atom is
Not quite — the answer is D.
l = 2 represents the d-subshell. The number of orbitals in this subshell is 2l + 1 = 5 and each orbital holds 2 electrons, giving 5 × 2 = 10 electrons. Option A incorrectly counts only the spin states of a single orbital; Option B counts the number of orbitals rather than electrons; Option C is an intermediate wrong value; Option D is the correct total.
Q6Important PYQ Mixed Concepts
For an electron in a 3d orbital, the possible values of n and l are respectively
Not quite — the answer is B.
For a 3d orbital, the principal quantum number n = 3 and d corresponds to azimuthal quantum number l = 2. Option A gives the 3s configuration. Option C gives a 2p electron. Option D represents a 4f orbital where l = 3.
Q7Bohr Model for Hydrogen Atom
The radius of the nth Bohr orbit in a hydrogen atom is proportional to which of the following?
Not quite — the answer is A.
Bohr radius formula: rₙ = 0.529 × n² Å, so radius ∝ n². Option B (n) would imply linear scaling, which is incorrect — radius grows faster because centripetal and electrostatic forces balance at n²-dependent distances.
Q8Bohr Model for Hydrogen Atom
The value of Bohr radius (radius of first orbit of hydrogen) is
Not quite — the answer is A.
Bohr radius a₀ = 0.529 Å = 0.529 × 10⁻¹⁰ m. Option B is r₂ (n=2 orbit radius). Option C has wrong power of 10 (nm vs Å scale).
Q9Atomic Models
Which model proposed the atom as a uniformly positive sphere with embedded electrons?
Not quite — the answer is A.
Thomson's plum pudding model pictured the atom as a sphere of uniform positive charge with electrons embedded like plums. It proposed no nucleus and no orbits — both later disproved.
Q10Atomic Models
Which experiment led to the rejection of Thomson's plum pudding model?
Not quite — the answer is B.
Rutherford's gold foil experiment showed that most alpha particles passed straight through while a few deflected at large angles — impossible if positive charge were spread uniformly as Thomson proposed.
Q11Towards Quantum Mechanical Model
According to de Broglie, moving matter exhibits which nature?
Not quite — the answer is C.
All moving matter exhibits dual nature — both wave and particle — as proposed by de Broglie. Option D is a trap: dual nature applies to ALL matter, not just charged particles. Option A/B are incomplete.
Q12Towards Quantum Mechanical Model
The de Broglie wavelength of a particle is correctly expressed as
Not quite — the answer is A.
de Broglie equation is λ = h/mv, where h is Planck's constant and mv is momentum. Option B inverts the relationship. Option C gives units of J²·s, not meters.
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Get RankUp on Google PlayQ13Quantum Mechanical Model of Atom
What does the wave function (ψ) represent in quantum mechanics?
Not quite — the answer is C.
ψ is a mathematical function representing probability amplitude; it has no direct physical meaning but ψ² gives the probability density of locating the electron. It does not represent energy or momentum directly.
Q14Quantum Mechanical Model of Atom
The quantity ψ² in quantum mechanics represents which of the following?
Not quite — the answer is C.
ψ² (probability density) gives the likelihood of finding an electron in a given region of space. It is always positive and real. Charge density is a different concept involving electron charge distribution.
Q15Discovery of Subatomic Particles
Which experiment led to the discovery of the electron?
Not quite — the answer is A.
J.J. Thomson's cathode ray discharge tube experiment revealed a negatively charged particle (electron) common to all matter. Gold foil experiment (Rutherford) discovered the nucleus; oil drop experiment measured electron charge.
Q16Discovery of Subatomic Particles
The charge on the electron was directly measured by which experiment?
Not quite — the answer is B.
Millikan's oil drop experiment (1909) determined the charge on the electron as 1.6 × 10⁻¹⁹ C by balancing gravitational and electric forces on charged oil droplets. Cathode ray experiment measured e/m ratio, not charge alone.
Q17Grand Test
Which set of quantum numbers is possible for an electron?
Not quite — the answer is A.
For n=3, l can be 0, 1 or 2; for l=2, m ranges from −2 to +2, so n=3,l=2,m=−2,s=+1/2 is valid. Option B violates l<n (l=2 equals n=2). Option C violates l<n (l=3 equals n=3). Option D violates the rule |m|≤l (m=1 > l=0).
Q18Grand Test
An electron in a hydrogen atom moves from n=4 to n=2. The emitted photon belongs to which series?
Not quite — the answer is B.
Transitions ending at n=2 form the Balmer series. Lyman series ends at n=1; Paschen ends at n=3; Brackett ends at n=4 as the terminal level, not the starting level.
Q19Mixed Revision
Which quantum number determines the number of subshells in a shell?
Not quite — the answer is A.
For a shell with principal quantum number n, the possible l values are 0 to n-1, giving n subshells. The magnetic quantum number determines orbital orientation, not subshell count.
Q20Mixed Revision
How many electrons can occupy all orbitals with n=3?
Not quite — the answer is C.
A shell has maximum electron capacity 2n2; for n=3 this gives 18 electrons. The value 9 represents the number of orbitals in n=3 shell, and 32 is the capacity of n=4.
Q21Discovery of Subatomic Particles
Who is credited with the discovery of canal rays (anode rays)?
Not quite — the answer is C.
E. Goldstein (1886) discovered canal rays (positive rays) by using perforated cathode in discharge tubes. Thomson discovered the electron; Chadwick discovered the neutron.
Q22Discovery of Subatomic Particles
Who is credited with the discovery of the neutron?
Not quite — the answer is D.
James Chadwick (1932) discovered the neutron by bombarding beryllium with alpha particles, producing neutral particles of mass ~1 amu. This completed the trio of subatomic particles.
Q23Discovery of Subatomic Particles
Cathode rays consist of which particles?
Not quite — the answer is A.
Cathode rays are streams of electrons (negatively charged), as proved by their deflection toward the positive plate in electric fields. They are independent of the cathode material and gas used.
Q24Discovery of Subatomic Particles
The charge-to-mass (e/m) ratio of the electron was first determined by whom?
Not quite — the answer is B.
J.J. Thomson measured the e/m ratio of cathode rays as 1.758 × 10¹¹ C/kg, proving these particles were identical regardless of cathode material. This e/m value is ~1836 times greater than that of the proton.
ELITE question · AIR under 50 level
This chapter has 323 ELITE questions for students aiming at the very top. They are only in the app.
Unlock ELITE questions in the appKey Atomic Concepts
Quick revision: most questions in this chapter test these facts.
| Concept | Key Fact |
|---|---|
| Bohr model | En = −13.6 Z²/n² eV; rn = 0.529 n²/Z Å; applies to H-like species only |
| Quantum numbers | n (shell), l (subshell: 0=s,1=p,2=d,3=f), ml (−l to +l), ms (+½ or −½) |
| Aufbau principle | Fill orbitals in order of increasing (n+l); if (n+l) same, lower n fills first |
| Pauli's exclusion | No two electrons in an atom can have all four quantum numbers identical |
| Hund's rule | Every orbital in a subshell gets one electron before any gets a second |
| De Broglie | λ = h/mv; wave-particle duality of matter |
What the app covers in this chapter
830 questions in total, each with a detailed explanation.
| Electronic Configuration of Atoms | 118 |
| Quantum Numbers | 101 |
| Important PYQ Mixed Concepts | 100 |
| Bohr Model for Hydrogen Atom | 98 |
| Atomic Models | 79 |
| Towards Quantum Mechanical Model | 79 |
| Quantum Mechanical Model of Atom | 78 |
| Discovery of Subatomic Particles | 61 |
| Grand Test | 59 |
| Mixed Revision | 57 |
Questions students ask
Is Structure of Atom important for NEET?
Yes — questions on Bohr model calculations, quantum numbers, electronic configuration and de Broglie equation appear every year. Understanding this chapter is essential for Chemical Bonding and d-block chemistry.
Which topics should I revise first?
Focus on Bohr model energy/radius formulas, valid quantum number sets, electronic configuration rules (Aufbau, Pauli, Hund's), and de Broglie wavelength calculations.
How many questions from this chapter are on RankUp?
The RankUp app has 830 questions on Structure of Atom, including 323 ELITE questions. Every question has a detailed explanation.
