Answer: iron (A ≈ 56).
- A hydrogen
- B helium
- C iron (A ≈ 56)
- D uranium
Correct answer: C. iron (A ≈ 56)
Explanation: The binding energy per nucleon curve peaks near iron (A ≈ 56), the most stable region.
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.