Assertion (A): Energy is released when heavy nuclei undergo fission or light nuclei undergo fusion.
Reason (R): For heavy nuclei, binding energy per nucleon increases with increasing (Z) while for light nuclei, it decreases with increasing (Z).
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true as both fission and fusion release energy. Reason (R) is false because binding energy per nucleon for heavy nuclei decreases with increasing (Z) (after Fe) and increases for light nuclei (up to Fe). Thus, (A) is true, (R) is false.
Assertion (A): Size of nucleus determined electron scattering and (alpha)-scattering are same.
Reason (R): Electron scattering or by (alpha)-scattering is controlled by distribution of charge in nucleus.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
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Assertion (A) is true; both methods estimate nuclear size based on charge distribution. Reason (R) is true; both electron and alpha scattering probe nuclear charge distribution. (R) correctly explains (A) as the interaction with charge distribution determines the 'size' measured.
Assertion (A): It is very easy to detect neutrino in nature.
Reason (R): It has high affinity to interact with matter.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is false; neutrinos are extremely difficult to detect due to very weak interactions. Reason (R) is also false; neutrinos have very low affinity to interact with matter. Therefore, both (A) and (R) are false.
Assertion (A): More energy is released in fusion than fission per nucleon.
Reason (R): More number of nucleons takes part in fusion.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true; fusion releases significantly more energy per nucleon than fission. Reason (R) is false; fusion involves lighter nuclei (fewer nucleons) compared to fission.
The higher energy release per nucleon is due to the greater increase in binding energy per nucleon.
Assertion (A): Deuterium is a good moderator of fast neutrons.
Reason (R): Fast neutrons transfer 90% of their kinetic energy to the nuclei of the moderator in an elastic collision.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true. Deuterium's mass is close to a neutron's, making it efficient for moderation. Reason (R) is true; in elastic collision with deuterium, neutrons lose about 89% of their kinetic energy. (R) is the correct explanation for (A).
Assertion (A): Beryllium can be used as a moderator in nuclear fission reactor.
Reason (R): A fast moving electron on collision with a light stationary particle loses most of its energy in nuclear reactor.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true; Beryllium is a suitable moderator due to low mass and absorption.
Reason (R) is false; moderation involves neutrons, not electrons. Electrons are not used for moderating neutrons in nuclear reactors. Thus, (A) is true, but (R) is false.
Assertion (A): Nuclear force is short range while gravitation and electric force are universal.
Reason (R): Nuclear force does not follow inverse square law.
1. Both (A) & (R) are true and the (R) is the correct explanation of the (A)
2. Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
3. (A) is true but (R) is false
4. Both (A) and (R) are false
View Answer
Assertion (A) is true; nuclear force is short-range, while gravitational and electric forces are long-range.
Reason (R) is true; nuclear force has a complex dependence, not \(1/r^2\). (R) correctly explains (A) as the absence of inverse square law behavior is characteristic of short-range forces.