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Consider a nucleus with mass number A = 110. Referring to a graph of binding energy per nucleon (B/A) vs mass number A, fission splits this nucleus into two fragments. Which pair of mass numbers for the resulting fragments is most energetically favourable (releases energy)?
- 80 and 30
- 60 and 50
- 100 and 10
- 90 and 20
Correct answer: 60 and 50
Solution
The B/A vs A curve peaks around A ~ 56. Fragments with A = 60 and A = 50 are both near the peak and thus have higher B/A than the parent at A = 110, making fission energetically favourable. Pairs like 80+30, 100+10, or 90+20 have one fragment far from the peak with lower B/A.
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