Answer: A − 4 and Z − 2.
- A A − 4 and Z − 2
- B A − 2 and Z − 4
- C A − 4 and Z − 1
- D A and Z − 2
Correct answer: A. A − 4 and Z − 2
Explanation: An alpha particle carries away 4 nucleons and 2 protons, so A decreases by 4 and Z by 2.
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.