Which fact is true during a fission chain reaction?
A. The number of freely-moving neutrons increases over time.
B. The number of freely-moving neutrons decreases over time.
C. The total number of protons will decrease over time.
D. The total number of protons will increase over time.
A. The number of freely-moving neutrons increases over time is true during a fission chain reaction.
A. The number of freely-moving neutrons increases over time.
To determine which fact is true during a fission chain reaction, let's break down each statement.
A. The number of freely-moving neutrons increases over time.
In a fission chain reaction, a nucleus is split into two or more smaller nuclei, releasing energy and additional neutrons. Some of these neutrons may be captured by other nuclei, causing them to split as well. This leads to an increase in the number of freely-moving neutrons, making option A true.
B. The number of freely-moving neutrons decreases over time.
Since the fission process releases additional neutrons, and some of these neutrons go on to cause further fission reactions, the number of freely-moving neutrons generally increases over time. Therefore, option B is not true.
C. The total number of protons will decrease over time.
During a fission chain reaction, the number of protons remains constant as protons are not directly involved in the splitting of nuclei. The primary focus is on the behavior of neutrons. Therefore, option C is not true.
D. The total number of protons will increase over time.
Similar to the previous statement, the number of protons remains constant during a fission chain reaction. Therefore, option D is not true.
In conclusion, option A is the correct statement.