Answer: increases by 1.
- A increases by 1
- B decreases by 1
- C remains unchanged
- D increases by 2
Correct answer: A. increases by 1
Explanation: A neutron converts to a proton, so Z increases by 1 while the mass number stays the same.
Binding energy per nucleon rises sharply for light nuclei, peaks around iron-56 (the most stable nucleus), then slowly declines for heavier nuclei - which is exactly why fusing light nuclei or splitting heavy nuclei both release energy: each moves the products toward this stability peak.
Concept context
Radioactivity, nuclear reactions, fission, fusion, and binding energy.