A nucleus of mass number 240 splits into two fragments each of mass number 120. Binding energy per nucleon is 7.6 MeV for the parent and 8.5 MeV for each fragment. The total gain in binding energy is:
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Question

A nucleus of mass number 240 splits into two fragments each of mass number 120. Binding energy per nucleon is 7.6 MeV for the parent and 8.5 MeV for each fragment. The total gain in binding energy is:

G1 Physics · Accepted Answer

Initial binding energy = 240 × 7.6 = 1824 MeV. Final binding energy = (120 × 8.5) + (120 × 8.5) = 2040 MeV. Energy released = final BE − initial BE = 2040 − 1824 = 216 MeV. Final answer: Option D (216 MeV). The supplied book solution reports 9.4 MeV because it incorrectly subtracts per-nucleon quantities without multiplying by nucleon counts.