NEET Physics: Nuclear fission and fusion Practice Questions
13 free multiple-choice questions on Nuclear fission and fusion (Atoms and Nuclei) for NEET Physics, each with the correct answer and a step-by-step explanation. Attempt a question, then reveal the solution to check your reasoning.
Practice thousands more NEET questions in the app →Q1. Which term describes the nucleus of an atom that has a definite number of protons but a variable number of neutrons?
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Correct answer: A — Isotope
An isotope is a variant of an element that has the same number of protons but a different number of neutrons.
Q2. Which of the following is a necessary condition for sustaining a nuclear chain reaction in a reactor?
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Correct answer: C — Sufficient fissile material and moderation
A chain reaction requires a sufficient amount of fissile fuel and a moderator to slow down neutrons effectively, allowing them to cause further fission.
Q3. Nuclear fusion reactions generally release energy because the resulting nucleus is more stable than the initial reactants. This stability is determined by:
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Correct answer: B — The difference in binding energy between products and reactants.
Energy is released during fusion because the products have a higher total binding energy per nucleon compared to the reactants, resulting in a net energy release.
Q4. In the context of nuclear reactions, a system is considered more stable when its nucleus has a higher binding energy per nucleon. This stability is related to:
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Correct answer: B — The mass defect.
A higher binding energy per nucleon indicates a more stable nucleus, as it requires more energy to break it apart.
Q5. In the context of nuclear reactions, the term 'binding energy' primarily refers to:
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Correct answer: C — The energy released when nucleons bind together
Binding energy is the energy equivalent of the mass defect; it is the energy required to break the nucleus apart into its constituent protons and neutrons.
Q6. Nuclear fusion generally requires extremely high temperatures and pressures to overcome the electrostatic repulsion between positively charged nuclei.
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Correct answer: C — High temperature and high pressure
Fusion requires immense energy to overcome the repulsive Coulomb force, which necessitates very high kinetic energy, achieved by high temperatures and pressures.
Q7. The binding energy of a nucleus is defined by the energy required to separate its nucleons. This energy is released when the nucleus is formed. Which statement correctly describes the relationship between mass defect and binding energy?
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Correct answer: B — Mass defect is directly proportional to the binding energy released.
The binding energy is the energy equivalent of the mass defect (Δm = (Z mₚ + N mₙ) - M₍actual)). A larger mass defect corresponds to a greater amount of energy released (binding energy).
Q8. When nucleons come together in a fusion reaction, the total mass of the resulting nucleus is slightly less than the sum of the masses of the individual separated nuclei. This mass difference is converted into energy according to which principle?
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Correct answer: D — Mass-Energy Equivalence (E=mc²).
The energy released during mass conversion is governed by Einstein's mass-energy equivalence equation, E=mc². The difference in mass (mass defect) is converted directly into energy.
Q9. Nuclear fission is the process where a heavy nucleus splits into two or more lighter nuclei. This process primarily requires:
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Correct answer: D — The absorption of a neutron by a heavy nucleus.
Fission occurs when a heavy nucleus (like Uranium-235) absorbs a neutron, causing it to split into smaller fragments and release energy.
Q10. Which one of the following statements correctly describes the relationship between mass defect and nuclear binding energy?
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Correct answer: B — The mass defect is directly proportional to the binding energy.
The mass defect (the difference between the mass of the nucleus and the sum of the masses of its constituent nucleons) is directly related to the total energy released during the nuclear reaction, which is the binding energy.
Q11. Which of the following conditions is most essential for achieving sustained nuclear fusion in stars?
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Correct answer: C — Extremely high temperature and high pressure
Nuclear fusion requires overcoming the electrostatic repulsion between nuclei, which necessitates extremely high temperatures (to provide sufficient kinetic energy) and high pressures (to ensure sufficient density) for the fusion process to occur and sustain itself.
Q12. Nuclear fusion reactions typically occur when two light nuclei combine to form a heavier nucleus, releasing energy. Which condition is generally required to initiate a fusion reaction?
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Correct answer: C — High temperature and high pressure
Fusion requires extremely high temperatures and pressures to overcome the electrostatic repulsion between the nuclei and allow them to fuse.
Q13. In a nuclear reaction, fusion typically occurs when light nuclei combine to form a heavier nucleus. What is the primary condition required to initiate and sustain a fusion reaction?
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Correct answer: A — The presence of high kinetic energy to overcome the electrostatic repulsion.
Fusion requires overcoming the electrostatic repulsion (Coulomb barrier) between the positively charged nuclei. This is achieved by providing sufficient kinetic energy.
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