UET UG Physics Booster Test 2- Nuclear Forces and Stability -

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CUET UG Physics Booster Test 2- Nuclear Forces and Stability

⏱️ 30 Minutes

❓ 20 Questions

📌 Answers are locked once submitted — results and explanations appear at the end.

CUET UG Physics Booster Test 2- Nuclear Forces and Stability

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QUESTION 1 OF 20

Incorrect statement about the strong nuclear binding force,

Answer Review

1 Incorrect statement about the strong nuclear binding force,

A It binds both protons and neutrons into the tiny nuclear volume.

B It is sufficiently strong to produce a binding energy of a few MeV per nucleon.

C It governs the motion of atomic electrons in their orbitals.

D It must overcome the repulsion between positively charged protons.

💡 Short Explanation

�� Strong force acts inside the nucleus. �� Electrons are governed by electromagnetic force. �� Nuclear binding energy is of MeV scale.

✅ Correct Answer Explanation

The strong nuclear force acts between nucleons and binds protons and neutrons within the nucleus. Electron motion in atomic orbitals is governed by electromagnetic attraction between electrons and the nucleus, not by the strong force. Therefore, option C is correct.

❓ Why Other Options Are Incorrect

�� Option A → Correct because strong force binds nucleons.
�� Option B → Correct because nuclear binding energies are typically a few MeV per nucleon.
�� Option D → Correct because strong force must overcome Coulomb repulsion.

🎯 Strategy

Used

Odd One Out

Application:

Identify the statement describing atomic rather than nuclear behavior.

Final Logic:

Electron motion is governed by electromagnetic force, not strong force.

🧠 Memory Trick

Electrons → EM Force

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Strong Nuclear Force

2 Electrostatic force behaviors inside the nucleus statements,
1. Repulsion exists strongly between positively charged protons.
2. It dominates over the strong nuclear force at all distances.
3. It falls rapidly to zero beyond a few femtometres.
4. It acts universally between charges, unlike the nuclear force.

A (1), (4)

B (2), (3)

C (1), (2), (4)

D (1), (3), (4)

💡 Short Explanation

�� Coulomb force acts between charges. �� Proton-proton repulsion exists. �� Coulomb force is long-ranged.

✅ Correct Answer Explanation

Statement 1 is correct because positively charged protons repel each other. Statement 2 is incorrect because strong nuclear force dominates at nuclear distances. Statement 3 is incorrect because Coulomb force does not fall rapidly to zero; it is long-ranged. Statement 4 is correct because Coulomb interaction acts universally between electric charges. Therefore, statements 1 and 4 are correct.

❓ Why Other Options Are Incorrect

�� Option B → Includes statements 2 and 3, both incorrect.
�� Option C → Includes statement 2, which is incorrect.
�� Option D → Includes statement 3, which is incorrect.

🎯 Strategy

Used

Elimination

Application:

Compare long-range Coulomb force with short-range nuclear force.

Final Logic:

Only statements 1 and 4 are valid.

🧠 Memory Trick

Coulomb = Charge Everywhere

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Coulomb Repulsion

3 The distance at which the attractive and repulsive forces between two nucleons perfectly balance to yield minimum potential energy is

A 0.8 fm

B 1.2 fm

C 4.0 fm

D 8.0 fm

💡 Short Explanation

�� Potential energy minimum corresponds to stable separation. �� Attractive and repulsive forces balance. �� Occurs near 0.8 fm.

✅ Correct Answer Explanation

At approximately 0.8 fm, the attractive nuclear force and short-range repulsive force balance each other. This corresponds to the minimum of the nucleon potential-energy curve and the most stable separation. Therefore, option A is correct.

❓ Why Other Options Are Incorrect

�� Option B → Larger than the equilibrium separation.
�� Option C → Outside the region of strongest nuclear attraction.
�� Option D → Far beyond nuclear-force range.

🎯 Strategy

Used

Memory-Based Recall

Application:

Recall the standard nucleon potential-energy graph.

Final Logic:

Minimum potential energy occurs near 0.8 fm.

🧠 Memory Trick

r₀ = 0.8 fm

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Nuclear Potential Energy

4 If a pair of nucleons is forced to a separation distance of 0.5 fm, what is the nature of the force and the minimal distance r₀ for this system?

A Attractive, 1.2 fm

B Attractive, 0.8 fm

C Repulsive, 1.2 fm

D Repulsive, 0.8 fm

💡 Short Explanation

�� 0.5 fm lies inside the repulsive core. �� Equilibrium distance is 0.8 fm. �� Strong repulsion prevents collapse.

✅ Correct Answer Explanation

At separations below about 0.8 fm, nucleons experience a strong repulsive force. The equilibrium separation corresponding to minimum potential energy remains approximately 0.8 fm. Therefore, option D is correct.

❓ Why Other Options Are Incorrect

�� Option A → Both force nature and distance are incorrect.
�� Option B → Force is not attractive at 0.5 fm.
�� Option C → Equilibrium distance is not 1.2 fm.

🎯 Strategy

Used

Contextual/Tonal Matching

Application:

Use the nucleon force-versus-distance graph.

Final Logic:

0.5 fm → Repulsive region; r₀ → 0.8 fm.

🧠 Memory Trick

Below 0.8 → Push

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Nuclear Force Characteristics

5 Match List I with List II concerning force characteristics

List I	List II
1. Strong nuclear force range	a. Practically infinite
2. Gravitational force range	b. A few femtometres
3. Force behavior for distance > a few fm	c. Saturation of binding energy
4. Consequence of short-ranged force	d. Rapid fall to zero

A (1)-b, (2)-a, (3)-d, (4)-c

B (1)-a, (2)-b, (3)-c, (4)-d

C (1)-d, (2)-c, (3)-b, (4)-a

D (1)-b, (2)-d, (3)-a, (4)-c

💡 Short Explanation

�� Nuclear force is short-ranged. �� Gravity is infinite-ranged. �� Saturation arises from limited interaction range.

✅ Correct Answer Explanation

1 → b : Strong nuclear force acts over a few femtometres. 2 → a : Gravitational force has effectively infinite range. 3 → d : Nuclear force rapidly falls to zero beyond a few femtometres. 4 → c : Short-range interaction leads to saturation of binding energy. Thus, option A is correct.

❓ Why Other Options Are Incorrect

�� Option B → Nuclear and gravitational ranges are interchanged.
�� Option C → Multiple incorrect matches.
�� Option D → Force behavior beyond a few fm is incorrectly matched.

🎯 Strategy

Used

Option Grouping

Application:

Match each force property with its defining characteristic.

Final Logic:

Short range → few fm → rapid fall → saturation.

🧠 Memory Trick

Few fm → Saturation

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Range and Saturation of Nuclear Force

6 The nuclear force is effective exclusively at the __________ scale, while macroscopic interactions are generally driven by the __________ scale forces like gravity.

A Angstrom, Femtometre

B Femtometre, Infinite

C Nanometre, Picometre

D Macroscopic, Microscopic

💡 Short Explanation

�� Nuclear force acts over femtometres. �� Gravity has infinite range. �� Nuclear effects are microscopic.

✅ Correct Answer Explanation

The strong nuclear force is effective over distances of a few femtometres. Gravity, which governs many macroscopic phenomena, has an effectively infinite range. Therefore, option B is correct.

❓ Why Other Options Are Incorrect

�� Option A → Scales are incorrect.
�� Option C → Does not represent nuclear-force range.
�� Option D → Not specific physical scales.

🎯 Strategy

Used

Dimensional/Unit Analysis

Application:

Compare nuclear and gravitational interaction ranges.

Final Logic:

Nuclear → fm, Gravity → infinite range.

🧠 Memory Trick

Strong = fm, Gravity = Infinite

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Range of Nuclear Force

7 Because the nuclear force is highly short-ranged, a nucleon in a sufficiently large nucleus

A interacts only with its nearest neighbours up to a defined limited distance

B shares its binding energy equally across all nucleons simultaneously

C experiences a net repulsive force from the majority of distant nucleons

D creates a total binding energy directly proportional to the square of the mass number

💡 Short Explanation

�� Nuclear force is short-ranged. �� Only nearby nucleons interact strongly. �� Leads to saturation.

✅ Correct Answer Explanation

A nucleon interacts significantly only with neighbouring nucleons lying within the short range of the nuclear force. Distant nucleons contribute negligibly. Therefore, option A is correct.

❓ Why Other Options Are Incorrect

�� Option B → Binding energy is not shared equally among all nucleons.
�� Option C → Distant nucleons exert negligible influence.
�� Option D → Binding energy does not vary as A².

🎯 Strategy

Used

Elimination

Application:

Apply the saturation property of nuclear force.

Final Logic:

Short range restricts interactions to nearby nucleons.

🧠 Memory Trick

Near Neighbours Matter

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Saturation Property

8 Nucleons residing on the surface of a large nucleus

A possess a maximum possible number of p neighbours

B have fewer interacting neighbours compared to nucleons deep inside

C cause the overall binding energy per nucleon to fluctuate wildly with every added nucleon

D dominate the total mass of any given heavy element

💡 Short Explanation

�� Surface nucleons have fewer neighbours. �� Interior nucleons are more strongly bound. �� Surface effect lowers average binding energy.

✅ Correct Answer Explanation

A surface nucleon lacks neighbouring nucleons on one side of the nucleus. Consequently, it interacts with fewer nucleons than an interior nucleon. Therefore, option B is correct.

❓ Why Other Options Are Incorrect

�� Option A → Maximum neighbours occur for interior nucleons.
�� Option C → Binding energy changes gradually.
�� Option D → Surface nucleons do not dominate mass.

🎯 Strategy

Used

Elimination

Application:

Compare interior and surface nucleons.

Final Logic:

Surface nucleons have fewer neighbouring interactions.

🧠 Memory Trick

Surface = Fewer Friends

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Surface Effects in Nuclei

9 Correct statements regarding specific nucleon interactions
1. The force between two protons is approximately the same as between two neutrons.
2. The force between a proton and a neutron is vastly different from p-p interactions.
3. Nuclear force heavily depends on the presence of the elementary charge e.
4. n-n interaction is governed entirely by Coulomb's law.

A Only (1)

B (1), (2)

C (2), (3)

D (1), (4)

💡 Short Explanation

�� Nuclear force is charge independent. �� p-p and n-n interactions are similar. �� Coulomb law does not govern n-n interaction.

✅ Correct Answer Explanation

Statement 1 is correct because nuclear force between p-p and n-n pairs is approximately equal. Statement 2 is incorrect because p-n interactions are not vastly different. Statement 3 is incorrect because nuclear force is nearly independent of charge. Statement 4 is incorrect because neutrons have no electric charge and interact through nuclear force. Therefore, only statement 1 is correct.

❓ Why Other Options Are Incorrect

�� Option B → Includes statement 2, which is incorrect.
�� Option C → Statements 2 and 3 are incorrect.
�� Option D → Includes statement 4, which is incorrect.

🎯 Strategy

Used

Elimination

Application:

Use the principle of charge independence.

Final Logic:

Only statement 1 remains valid.

🧠 Memory Trick

p-p ≈ n-n

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Charge Independence of Nuclear Force

10 Incorrect statement regarding the charge independence of the nuclear force

A The strong force between proton-proton is roughly the same as neutron-neutron.

B The nuclear force ignores the specific electric charge state of the nucleons.

C The attractive nuclear force between a proton and a neutron exists solely because of their differing electric charges.

D The near equality of n-n and p-p forces serves as evidence for charge independence.

💡 Short Explanation

�� Nuclear force is independent of charge. �� p-p and n-n forces are nearly equal. �� p-n attraction is not due to charge difference.

✅ Correct Answer Explanation

The nuclear force arises from the strong interaction and is largely independent of electric charge. The attraction between a proton and a neutron is not caused by their differing charges. Hence, option C is the incorrect statement.

❓ Why Other Options Are Incorrect

�� Option A → Correct evidence for charge independence.
�� Option B → Correct description of nuclear force.
�� Option D → Correct experimental observation.

🎯 Strategy

Used

Odd One Out

Application:

Identify the statement that incorrectly attributes nuclear force to charge.

Final Logic:

Strong interaction, not charge difference, produces nuclear attraction.

🧠 Memory Trick

Strong ≠ Charge

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Charge Independence of Nuclear Force

11 Which of the following effectively describes the relative sequence of force strengths between two protons separated by 1 fm inside a nucleus?

A Nuclear Force > Coulomb Force > Gravitational Force

B Coulomb Force > Nuclear Force > Gravitational Force

C Gravitational Force > Coulomb Force > Nuclear Force

D Nuclear Force > Gravitational Force > Coulomb Force

💡 Short Explanation

�� Strong nuclear force dominates at nuclear distances. �� Coulomb force is weaker than the strong force. �� Gravity is negligible.

✅ Correct Answer Explanation

At a separation of about 1 fm, the strong nuclear force is the dominant interaction between nucleons. Coulomb repulsion between protons is significant but weaker. Gravitational attraction is extremely small compared with both. Therefore, the correct order is: Nuclear Force > Coulomb Force > Gravitational Force

❓ Why Other Options Are Incorrect

�� Option B → Coulomb force is not stronger than the strong force at nuclear distances.
�� Option C → Gravity is the weakest interaction, not the strongest.
�� Option D → Coulomb force is much stronger than gravity.

🎯 Strategy

Used

Option Grouping

Application:

Compare the relative magnitudes of the three forces.

Final Logic:

Strong > Coulomb > Gravity.

🧠 Memory Trick

Strong Wins, Gravity Loses

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Relative Strengths of Forces

12 In order to maintain structural integrity and not instantly fly apart, an atomic nucleus requires that

A the Coulomb force must be fully neutralized by orbiting electrons

B the strong nuclear force must continuously dominate over the internal Coulomb repulsive force

C the gravitational force must perfectly balance out the Coulomb repulsion

D the protons must periodically shed their positive charge

💡 Short Explanation

�� Protons repel each other. �� Strong force binds nucleons. �� Stable nuclei require strong-force dominance.

✅ Correct Answer Explanation

The positively charged protons inside a nucleus repel each other through Coulomb force. Stability is achieved only because the attractive strong nuclear force is stronger than the repulsive Coulomb force over nuclear distances. Therefore, option B is correct.

❓ Why Other Options Are Incorrect

�� Option A → Electrons do not neutralize proton repulsion inside the nucleus.
�� Option C → Gravity is far too weak.
�� Option D → Protons do not lose charge periodically.

🎯 Strategy

Used

Elimination

Application:

Identify the force responsible for nuclear stability.

Final Logic:

Strong force must exceed Coulomb repulsion.

🧠 Memory Trick

Strong Holds, Coulomb Pushes

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Nuclear Stability

13 Mathematical modeling of nuclear forces statements
1. It strictly follows a simple inverse-square relationship.
2. It possesses no uniquely simple mathematical form.
3. It differs structurally from Newton's law of gravitation.
4. It can be perfectly modelled using purely Coulombic equations.

A (2), (3), (4)

B (1), (4)

C (1), (2), (3)

D (2), (3)

💡 Short Explanation

�� Nuclear force is complex. �� No simple universal equation exists. �� It differs from gravitational and Coulomb forces.

✅ Correct Answer Explanation

Statement 1 is incorrect because nuclear force does not follow an inverse-square law. Statement 2 is correct because no uniquely simple mathematical expression describes nuclear force. Statement 3 is correct because its behavior differs significantly from Newtonian gravitation. Statement 4 is incorrect because Coulomb equations cannot fully model nuclear interactions. Therefore, statements 2 and 3 are correct.

❓ Why Other Options Are Incorrect

�� Option A → Includes statement 4, which is incorrect.
�� Option B → Statements 1 and 4 are incorrect.
�� Option C → Includes statement 1, which is incorrect.

🎯 Strategy

Used

Elimination

Application:

Compare nuclear-force behavior with known force laws.

Final Logic:

Only statements 2 and 3 correctly describe nuclear-force modeling.

🧠 Memory Trick

Strong Force ≠ Inverse Square

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Nature of Nuclear Force

14 Match List I with List II for the nuclear potential energy curve regions

List I	List II
1. Nucleon separation > 0.8 fm	a. Minimum potential energy reached
2. Nucleon separation < 0.8 fm	b. Indicates a strongly repulsive force
3. Nucleon separation = 0.8 fm	c. Indicates an attractive force
4. Gradient of potential curve for r < r₀	d. Strongly repulsive region

A (1)-c, (2)-d, (3)-a, (4)-b

B (1)-d, (2)-c, (3)-b, (4)-a

C (1)-a, (2)-b, (3)-c, (4)-d

D (1)-b, (2)-a, (3)-d, (4)-c

💡 Short Explanation

�� r > 0.8 fm gives attraction. �� r < 0.8 fm gives repulsion. �� r = 0.8 fm corresponds to minimum potential energy.

✅ Correct Answer Explanation

1 → c : Beyond 0.8 fm, the nuclear force is attractive. 2 → d : Below 0.8 fm lies the strongly repulsive region. 3 → a : At 0.8 fm, potential energy is minimum. 4 → b : The gradient for r < r₀ corresponds to a strongly repulsive force. Therefore, option A is correct.

❓ Why Other Options Are Incorrect

�� Option B → Attraction and repulsion regions are reversed.
�� Option C → Minimum-energy position is incorrectly matched.
�� Option D → Multiple curve features are mismatched.

🎯 Strategy

Used

Option Grouping

Application:

Associate each distance region with the corresponding potential-energy behavior.

Final Logic:

Above r₀ → attraction, below r₀ → repulsion, at r₀ → minimum energy.

🧠 Memory Trick

Above r₀ Pull, Below r₀ Push

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Nuclear Potential Energy Curve

15 Regarding the required parameters for stability in light atomic nuclei

A the ratio of neutrons to protons must mathematically exceed 3:2

B the number of neutrons must be minimized to zero

C the ratio of neutrons to protons should be strictly maintained around 1:1

D protons must drastically outnumber the neutrons

💡 Short Explanation

�� Light nuclei are stable near N = Z. �� Neutrons reduce proton repulsion. �� N/Z ≈ 1 is preferred.

✅ Correct Answer Explanation

For light nuclei, maximum stability is achieved when the neutron-to-proton ratio is approximately 1:1. This provides sufficient nuclear attraction while maintaining balance within the nucleus. Therefore, option C is correct.

❓ Why Other Options Are Incorrect

�� Option A → More suitable for heavier nuclei.
�� Option B → Neutrons are essential for stability.
�� Option D → Excess protons increase instability.

🎯 Strategy

Used

Memory-Based Recall

Application:

Recall the stability condition for light nuclei.

Final Logic:

Light nuclei require N ≈ Z.

🧠 Memory Trick

Light → 1:1

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Stability of Nuclei

16 As nuclei become progressively heavier, the necessary neutron to proton ratio required to overcome Coulomb repulsion and maintain stability shifts closer to:

A 1:1

B 2:1

C 3:2

D 4:3

💡 Short Explanation

�� Heavy nuclei contain many protons. �� Extra neutrons improve stability. �� N/Z ratio increases with mass number.

✅ Correct Answer Explanation

As the number of protons increases, Coulomb repulsion becomes stronger. Additional neutrons provide extra nuclear attraction without adding electrical repulsion. Thus the stability ratio shifts toward approximately 3:2. Therefore, option C is correct.

❓ Why Other Options Are Incorrect

�� Option A → Appropriate mainly for light nuclei.
�� Option B → Too large for most stable heavy nuclei.
�� Option D → Smaller than the typical heavy-nucleus value.

🎯 Strategy

Used

Memory-Based Recall

Application:

Recall the trend of the stability curve.

Final Logic:

Heavy nuclei require more neutrons than protons.

🧠 Memory Trick

Heavy → 3:2

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Neutron-Proton Ratio

17 Correct statements indicating nuclear instability
1. Nuclei featuring an excess of neutrons relative to the stable ratio are generally unstable.
2. Nuclei holding an excess of protons relative to the stable ratio are generally unstable.
3. Deviating widely from the stability ratio inherently prevents any form of decay.
4. Unstable nuclei exist entirely independently of the neutron-proton ratio.

A (1), (2)

B (3), (4)

C (1), (3)

D (2), (4)

💡 Short Explanation

�� Stability depends strongly on N/Z ratio. �� Excess neutrons can cause instability. �� Excess protons can also cause instability.

✅ Correct Answer Explanation

Statement 1 is correct because neutron-rich nuclei often undergo beta decay. Statement 2 is correct because proton-rich nuclei are generally unstable. Statement 3 is incorrect because deviation from stability promotes decay rather than preventing it. Statement 4 is incorrect because neutron-proton ratio is a major factor governing stability. Therefore, statements 1 and 2 are correct.

❓ Why Other Options Are Incorrect

�� Option B → Both statements are incorrect.
�� Option C → Includes statement 3, which is incorrect.
�� Option D → Includes statement 4, which is incorrect.

🎯 Strategy

Used

Elimination

Application:

Check each statement using the stability-band concept.

Final Logic:

Both neutron excess and proton excess can cause instability.

🧠 Memory Trick

Too Many N or P → Decay

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Nuclear Stability

18 Radioactivity serves as a fundamental sign of nuclear __________, fundamentally triggered when the nucleus possesses an __________ of distinct nucleons.

A Stability, Equilibrium

B Instability, Excess

C Expansion, Absence

D Fusion, Deficit

💡 Short Explanation

�� Radioactivity indicates instability. �� Nucleon imbalance causes decay. �� Unstable nuclei emit radiation.

✅ Correct Answer Explanation

Radioactivity is a direct indication of nuclear instability. Nuclei possessing an excess of neutrons or protons relative to the stable ratio tend to undergo radioactive decay. Therefore, option B is correct.

❓ Why Other Options Are Incorrect

�� Option A → Stability does not produce radioactivity.
�� Option C → Expansion and absence are unrelated.
�� Option D → Radioactivity is not equivalent to fusion.

🎯 Strategy

Used

Contextual/Tonal Matching

Application:

Associate radioactivity with unstable nuclei.

Final Logic:

Instability caused by nucleon excess leads to decay.

🧠 Memory Trick

Radioactivity = Instability

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Radioactivity

19 Incorrect statement regarding stable nuclear species distribution

A Nearly 90% of all identified isotopes naturally maintain perfect stability.

B Only about 10% of known isotopes across elements are completely stable.

C Maintaining stability heavily requires a very specific neutron to proton ratio.

D The majority of currently known isotopes are unstable and decay over time.

💡 Short Explanation

�� Most isotopes are radioactive. �� Stable isotopes are relatively few. �� Stability depends on N/Z ratio.

✅ Correct Answer Explanation

Only a small fraction of known isotopes are stable. Approximately 10% are stable, while the majority are radioactive. Therefore the claim that nearly 90% are stable is incorrect. Hence, option A is correct.

❓ Why Other Options Are Incorrect

�� Option B → Correct statement regarding stable isotope abundance.
�� Option C → Correct description of nuclear stability.
�� Option D → Correct because most isotopes are unstable.

🎯 Strategy

Used

Odd One Out

Application:

Identify the statement that contradicts known isotope statistics.

Final Logic:

Stable isotopes are the minority, not the majority.

🧠 Memory Trick

Stable ≈ 10%

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Stable and Unstable Isotopes

20 Artificial production and observation of unstable isotopes statements
1. They are synthesized by bombarding stable targets with alpha particles or neutrons.
2. They constitute the vast majority of the known pool of isotopes.
3. They can be independently identified via astronomical observations.
4. They automatically shift to a 3:2 ratio immediately upon creation.

A (2), (3), (4)

B (1), (2), (3)

C (1), (3), (4)

D (1), (4)

💡 Short Explanation

�� Radioisotopes can be artificially produced. �� Most known isotopes are unstable. �� Unstable isotopes can be detected astronomically.

✅ Correct Answer Explanation

Statement 1 is correct because unstable isotopes are commonly synthesized by bombardment reactions. Statement 2 is correct because radioactive isotopes form the majority of known isotopes. Statement 3 is correct because isotopes can be identified through astronomical observations and spectroscopic analysis. Statement 4 is incorrect because nuclei do not instantly adjust to a 3:2 ratio upon formation. Therefore, statements 1, 2 and 3 are correct.

❓ Why Other Options Are Incorrect

�� Option A → Includes statement 4, which is incorrect.
�� Option C → Includes statement 4, which is incorrect.
�� Option D → Omits statements 2 and 3 and includes statement 4.

🎯 Strategy

Used

Elimination

Application:

Verify each statement using radioisotope production and detection facts.

Final Logic:

Only statements 1, 2 and 3 are correct.

🧠 Memory Trick

Bombard → Radioisotope

📚 Class XII – NCERT Physics Part II – Chapter: Nuclei – Topic: Artificial Radioactivity and Radioisotopes

CUET UG Physics Booster Test 2- Nuclear Forces and Stability

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