Assertion (A): | The ratio of time taken for light emission from an atom to that for the release of nuclear energy in fission is 1:100. |
Reason (R): | Time taken for the light emission from an atom is of the order of 10-8s. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
Assertion (A): | Heavy water is a better moderator than normal water. |
Reason (R): | Heavy water absorbs neutrons more efficiently than normal water. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
Assertion (A): | In the process of nuclear fission, the fragments emit two or three neutrons as soon as they are formed and subsequently emit particles. |
Reason (R): | As the fragments contain an excess of neutrons over protons, emission of neutrons and particles bring their neutron/proton ratio to stable values. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |
Assertion (A): | Heavy water is preferred over ordinary water as a moderator in reactors. |
Reason (R): | Heavy water, used for slowing down the neutrons, has a lesser absorption probability of neutrons than ordinary water. |
1. | Both (A) and (R) are true and (R) is the correct explanation of (A). |
2. | Both (A) and (R) are true but (R) is not the correct explanation of (A). |
3. | (A) is true but (R) is false. |
4. | Both (A) and (R) are false. |