Answer: approximately independent of mass number.
- A approximately independent of mass number
- B proportional to A
- C proportional to A²
- D proportional to 1/A
Correct answer: A. approximately independent of mass number
Explanation: Since mass ∝ A and volume ∝ R³ ∝ A, the nuclear density is nearly constant for all nuclei.
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.