Answer: 1/8.
- A 1/8
- B 1/4
- C 1/6
- D 1/3
Correct answer: A. 1/8
Explanation: After n half-lives: N/N₀ = (1/2)<sup>n.</sup> After 3: (1/2)³ = 1/8.
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.