What does Atoms and Nuclei cover for NEET Physics?

12 lessons: Alpha Scattering, Atomic Masses, Binding Energy Variation, Bohr Model, Energy Levels Bohr, Hydrogen Spectrum, Mass Defect Binding Energy, Mass Energy Relation, Nuclear Composition Size, Nuclear Fission, Nuclear Fusion and Rutherford Model.

How often has Atoms and Nuclei come up in NEET past papers?

Our set of verified past papers has 15 questions from this unit, from NEET 2020, 2021, 2022, 2023, 2024, 2025 and 2026. Each is answered against the official NTA key.

Is the Atoms and Nuclei material free?

Yes. All 12 lessons and 96 practice questions are free, with no login needed.

Atoms and Nuclei

12 lessons

Topic index in NCERT order

12 of 12 lessons by the NCERT chapter they teach from, in book order. The page is the first printed page of your NCERT book the lesson cites; PYQs are the past NEET questions on that topic.

Class 11 Chemistry, Chapter 2

Hydrogen Spectrump. 452 PYQs

Class 12 Physics, Chapter 12

Alpha Scatteringp. 2911 PYQ
Rutherford Modelp. 2910 PYQs
Bohr Modelp. 2933 PYQs
Energy Levels Bohrp. 2951 PYQ

Class 12 Physics, Chapter 13

Alpha Scattering

8 MCQs1 PYQsWorked example

Easy Recall (2)Concept Trap (2)Direct Application (2)Calculation (2)

Atomic Masses

8 MCQs1 revision cardWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Binding Energy Variation

8 MCQs1 revision cardWorked example

Easy Recall (2)Concept Trap (2)Direct Application (2)Calculation (2)

Bohr Model

8 MCQs3 PYQs2 revision cardsWorked example

Easy Recall (3)Direct Application (3)Calculation (1)Concept Trap (1)

Energy Levels Bohr

8 MCQs1 PYQs1 revision cardWorked example

Easy Recall (3)Direct Application (3)Calculation (1)Concept Trap (1)

Hydrogen Spectrum

8 MCQs2 PYQs1 revision cardWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Mass Defect Binding Energy

8 MCQs1 PYQs2 revision cardsWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Mass Energy Relation

8 MCQs2 PYQs1 revision cardWorked example

Easy Recall (3)Direct Application (3)Calculation (1)Concept Trap (1)

Nuclear Composition Size

8 MCQs2 PYQs1 revision cardWorked example

Easy Recall (3)Direct Application (3)Concept Trap (1)Calculation (1)

Nuclear Fission

8 MCQs2 PYQs2 revision cardsWorked example

Easy Recall (3)Direct Application (3)Calculation (2)

Nuclear Fusion

8 MCQs1 PYQs2 revision cardsWorked example

Easy Recall (3)Direct Application (3)Calculation (2)

Rutherford Model

8 MCQsWorked example

Easy Recall (3)Direct Application (3)Calculation (2)

Past-paper questions from this unit

15 questions from NEET 2020, 2021, 2022, 2023, 2024, 2025, 2026. Answers verified against NTA official keys.

By year in our set: 2020 (2) · 2021 (1) · 2022 (3) · 2023 (3) · 2024 (2) · 2025 (1) · 2026 (3)

Lesson: Mass Energy Relation

NEET 2026

Consider the following nuclear reaction : ²³⁸U → ²³⁴Th + ⁴He. Take masses of ²³⁸U, ²³⁴Th and ⁴He as 238.050 u, 234.043 u and 4.003 u, respectively. The Q value for the reaction, in keV, is : [Given : 1 u = 931.5 MeV c⁻²]

13726

23730

33736

43740

NTA Answer: Option 1(final)

Report an error · Every fix is public: corrections log

Lesson: Alpha Scattering

NEET 2026

In Geiger-Marsden experiment, the number of scattered α-particles N(θ) is plotted as a function of scattering angle θ. Which of the following options represents the correct plot ?

NTA Answer: Option 3(final)

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Lesson: Bohr Model

NEET 2026

Consider that an electron is revolving in an excited state of Hydrogen atom with velocity √25.6 × 10⁵ ms⁻¹. The radius of the orbit is x × 10⁻⁹ m. The value of x is : [Take the mass of electron to be 9 × 10⁻³¹ kg, charge of electron = −1.6 × 10⁻¹⁹ C and 1/(4πε₀) = 9 × 10⁹ N m² C⁻²]

NTA Answer: Option 4(final)

Report an error · Every fix is public: corrections log

Lesson: Bohr Model

NEET 2025

A particle of mass m is moving around the origin with a constant force F pulling it towards the origin. If Bohr model is used to describe its motion, the radius of the nth orbit and the particle’s speed ν in the orbit depend on n as

1r ∝ n4/3; ν ∝ n–1/3

2r ∝ n1/3; ν ∝ n1/3

3r ∝ n1/3; ν ∝ n2/3

4r ∝ n2/3; ν ∝ n1/3

NTA Answer: Option 4(final)

Report an error · Every fix is public: corrections log

Lesson: Hydrogen Spectrum

NEET 2024Revised key

Match List I with List II. List I List II (Spectral Lines of (Wavelengths (nm)) Hydrogen for transitions from) A. n2 = 3 to n1 = 2 I. 410.2 B. n2 = 4 to n1 = 2 II. 434.1 C. n2 = 5 to n1 = 2 III. 656.3 D. n2 = 6 to n1 = 2 IV. 486.1 Choose the correct answer from the options given below:

1A-II, B-I, C-IV, D-III

2A-III, B-IV, C-II, D-I

3A-IV, B-III, C-I, D-II

4A-I, B-II, C-III, D-IV

NTA Answer: Option 2(revised_final)

Report an error · Every fix is public: corrections log

Lesson: Nuclear Composition Size

NEET 2024Revised key

²⁹⁰₈₂X —[α]→ Y —[e⁺]→ Z —[β⁻]→ P —[e⁻]→ Q In the nuclear emission stated above, the mass number and atomic number of the product Q respectively, are

1280, 81

2286, 80

3288, 82

4286, 81

NTA Answer: Option 4(revised_final)

Report an error · Every fix is public: corrections log

Lesson: Nuclear Fusion

NEET 2023

The half life of a radioactive substance is 20 minutes. In how much time, the activity of substance drops to (1/16)th of its initial value?

140 minutes

260 minutes

380 minutes

420 minutes

NTA Answer: Option 3(final)

Report an error · Every fix is public: corrections log

Lesson: Hydrogen Spectrum

NEET 2023

In hydrogen spectrum, the shortest wavelength in the Balmer series is λ. The shortest wavelength in the Bracket series is

14λ

29λ

316λ

42λ

NTA Answer: Option 1(final)

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Lesson: Bohr Model

NEET 2023

The radius of inner most orbit of hydrogen atom is 5.3 × 10⁻¹¹ m. What is the radius of third allowed orbit of hydrogen atom?

11.06 Å

21.59 Å

34.77 Å

40.53 Å

NTA Answer: Option 3(final)

Report an error · Every fix is public: corrections log

Lesson: Nuclear Composition Size

NEET 2022

In the given nuclear reaction, the element X is ²²₁₁Na → X + e⁺ + ν

1²²₁₂Mg

2²³₁₁Na

3²³₁₀Ne

4²²₁₀Ne

NTA Answer: Option 4(final)

Report an error · Every fix is public: corrections log

Lesson: Energy Levels Bohr

NEET 2022

Let T1 and T2 be the energy of an electron in the first and second excited states of hydrogen atoms, respectively. According to the Bohr’s model of an atom, the ratio T1 : T2 is

19 : 4

21 : 4

34 : 1

44 : 9

NTA Answer: Option 1(final)

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Lesson: Nuclear Fission

NEET 2022

A nucleus of mass number 189 splits into two nuclei having mass number 125 and 64. The ratio of radius of two daughter nuclei respectively is

125 : 16

21 : 1

34 : 5

45 : 4

NTA Answer: Option 4(final)

Report an error · Every fix is public: corrections log

Lesson: Mass Defect Binding Energy

NEET 2021

A nucleus with mass number 240 breaks into two fragments each of mass number 120, the binding energy per nucleon of unfragmented nuclei is 7.6 MeV while that of fragments is 8.5 MeV. The total gain in the Binding Energy in the process is

1216 MeV

20.9 MeV

39.4 MeV

4804 MeV

NTA Answer: Option 1(final)

Report an error · Every fix is public: corrections log

Lesson: Nuclear Fission

NEET 2020

When a uranium isotope 235 92U is bombarded with a neutron, it generates 89 36Kr , three neutrons and :

1103 36Kr

2144 56Ba

391 40Zr

4101 36Kr

NTA Answer: Option 2(final)

Report an error · Every fix is public: corrections log

Lesson: Mass Energy Relation

NEET 2020

The energy equivalent of 0.5 g of a substance is :

10.5 × 10¹³ J

24.5 × 10¹⁶ J

34.5 × 10¹³ J

41.5 × 10¹³ J

NTA Answer: Option 3(final)

Report an error · Every fix is public: corrections log

Exam traps and common mistakes in this unit

Lesson: Hydrogen Spectrum

Trap

Rydberg formula n1/n2 inversion

Category: Sign Convention

Student writes 1/λ = R(1/n_2² − 1/n_1²) (negative wavelength). Convention: n_2 > n_1, so 1/λ = R(1/n_1² − 1/n_2²) is positive.

When it triggers

Hydrogen spectrum problem with electronic transition.

How to avoid

n_1 is the LOWER (final for emission, initial for absorption) level. n_2 > n_1 is the HIGHER level. Bracket arrangement: smaller-n term first inside the parens. Result must be positive.

Lesson: Hydrogen Spectrum

Mistake

Writes Rydberg with n_1, n_2 in wrong order (gives negative wavelength).

Root cause: sign error

Correction

1/λ = R(1/n_1² - 1/n_2²) with n_2 > n_1. Smaller-n term first. Result must be positive.

Lesson: Nuclear Composition Size

Mistake

Treats nuclear radius as linear in A instead of A^(1/3).

Root cause: formula misuse

Correction

R = R_0 A^(1/3). Doubling A multiplies R by 2^(1/3) ≈ 1.26 (not 2). Implies constant nuclear density.

Formulas in this unit

Lesson: Atomic Masses

Mass-energy equivalence

E = m c^{2}

Einstein's mass-energy relation. 1 atomic mass unit = 931.5 MeV in energy units.

Symbol	Quantity	SI Unit
E	energy	J or MeV
m	mass	kg or u
c	speed of light	m/s

Valid when

Conversion of mass to energy (or vice versa)

Lesson: Binding Energy Variation

Mass defect and binding energy

B = Δ m \cdot c^{2}

Mass defect = sum of constituent masses minus nuclear mass. Binding energy = mass defect in energy units.

Symbol	Quantity	SI Unit
Z	proton number	-
N	neutron number	-
m_p, m_n	proton, neutron mass	u
B	binding energy	MeV

Valid when

Non-relativistic
Stable nucleus

Lesson: Bohr Model

Bohr energy levels

E_{n} = - \frac{13.6}{n ^{2}} eV

Energy of n-th Bohr orbit in hydrogen. n=1 ground state -13.6 eV; ionisation energy = 13.6 eV.

Symbol	Quantity	SI Unit
E_n	energy of n-th level	eV
n	principal quantum number	-

Valid when

Hydrogen atom
Non-relativistic

Lesson: Bohr Model

Bohr orbit radius

r_{n} = n^{2} a_{0}

Allowed radii in Bohr model of hydrogen atom. Quantised by integer n.

Symbol	Quantity	SI Unit
r_n	n-th orbit radius	m
a0	Bohr radius 5.29e-11	m
n	quantum number	-

Valid when

Hydrogen-like atom (single electron)
Non-relativistic

Lesson: Hydrogen Spectrum

Rydberg formula (hydrogen spectrum)

\frac{1}{λ} = R (\frac{1}{n _{1}^{2}} - \frac{1}{n _{2}^{2}})

Wavelengths of hydrogen spectral lines. R = 1.097e7 1/m. Lyman (n1=1, UV), Balmer (n1=2, visible), Paschen+ (IR).

Symbol	Quantity	SI Unit
lambda	wavelength	m
R	Rydberg constant	1/m
n1, n2	integers, n2>n1	-

Valid when

Hydrogen atom
Single electron transition

Lesson: Nuclear Composition Size

Nuclear radius scaling

R = R_{0} A^{1/3}

Nuclear radius scales with cube root of mass number A. Implies constant nuclear density.

Symbol	Quantity	SI Unit
R	nuclear radius	m
A	mass number	-
R0	~1.2e-15	m

Valid when

Spherical nucleus assumption

NEET question patterns in this unit

Lesson: Bohr Model

Bohr orbit: r_n = n² a_0; E_n = -13.6/n² eV. Compute for given n.

Direct ApplicationMedium

Common distractors

uses 1 n not 1 n squared

Misuses scaling

Lesson: Hydrogen Spectrum

Rydberg formula 1/λ = R(1/n_1² - 1/n_2²). Identify series and wavelength.

Multi StepMedium

Common distractors

swaps n1 n2

Inverts initial and final levels

Lesson: Mass Energy Relation

E = mc². Convert mass to energy or vice versa. 1 u → 931.5 MeV.

Direct ApplicationEasy

Common distractors

forgets c squared

Treats E = mc not mc²

Lesson: Nuclear Composition Size

Nuclear radius scales as A^(1/3). Compare two nuclei.

Direct ApplicationEasy

Common distractors

uses A or A squared

Uses linear or quadratic instead of cube root

Lesson: Nuclear Fission

Identify fission vs fusion; compute energy released from mass defect.

InterpretationMedium

Common distractors

confuses fission fusion

Conceptual swap

Questions about this unit

What does Atoms and Nuclei cover for NEET Physics?: 12 lessons: Alpha Scattering, Atomic Masses, Binding Energy Variation, Bohr Model, Energy Levels Bohr, Hydrogen Spectrum, Mass Defect Binding Energy, Mass Energy Relation, Nuclear Composition Size, Nuclear Fission, Nuclear Fusion and Rutherford Model.
How often has Atoms and Nuclei come up in NEET past papers?: Our set of verified past papers has 15 questions from this unit, from NEET 2020, 2021, 2022, 2023, 2024, 2025 and 2026. Each is answered against the official NTA key.
Is the Atoms and Nuclei material free?: Yes. All 12 lessons and 96 practice questions are free, with no login needed.