Q3. Which of the following statements is/are true of nuclear fission?
1. For the nuclear fission process to be self-sustaining, at least one neutron from each fission event must go on to split another nucleus.
2. If more than one neutron from each nuclear fission event causes another fission event, the process dies out and the reaction is said to be subcritical.
3. A fission bomb operates by suddenly combining two subcritical masses of fissionable material to form a supercritical mass.
a. 3 only
b. 1 and 3
c. 1 only
d. 2 and 3
e. 2 only
To determine which of the statements are true of nuclear fission, let's analyze each statement:
1. For the nuclear fission process to be self-sustaining, at least one neutron from each fission event must go on to split another nucleus.
To verify the truth of this statement, we need to understand the concept of a critical mass. A critical mass is the minimum amount of fissile material needed to sustain a nuclear chain reaction. In the case of nuclear fission, if more than one neutron from each fission event goes on to split another nucleus, the chain reaction will continue and the process will be self-sustaining. Therefore, statement 1 is true.
2. If more than one neutron from each nuclear fission event causes another fission event, the process dies out and the reaction is said to be subcritical.
To determine the accuracy of this statement, we need to understand the concept of subcriticality. If the number of neutrons produced in each fission event is less than one, the chain reaction will gradually decrease and eventually die out. In this case, the reaction is considered subcritical. So, statement 2 is also true.
3. A fission bomb operates by suddenly combining two subcritical masses of fissionable material to form a supercritical mass.
This statement describes the mechanism of a fission bomb and is known as the principle of a critical mass. A fission bomb, also known as an atomic bomb, relies on combining two subcritical masses (each individually unable to sustain a chain reaction) of fissile materials, such as uranium-235 or plutonium-239, to create a critical mass that can sustain a rapid, self-sustaining nuclear chain reaction. Therefore, statement 3 is true.
Based on our analysis, statements 1, 2, and 3 are all true. Therefore, the correct answer is b. 1 and 3.