A graph shows binding energy per nucleon (MeV, y-axis) against mass number A (x-axis). It rises steeply for light nuclei, flattens at a broad maximum of about 8.75 MeV near A = 56, and falls slowly to about 7.6 MeV at A = 238. Why does the fission of a nucleus with A ≈ 235 into two nuclei of intermediate mass release energy?
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The intermediate-mass products lie nearer the peak of the curve, so their binding energy per nucleon is greater (about 8.5 MeV against 7.6 MeV). The difference in total binding energy is released.
- A.
A smaller binding energy per nucleon in the products would need energy to be supplied, not released.
- C.
The number of nucleons is conserved in fission.
- D.
The curve shows heavy nuclei have a lower binding energy per nucleon than intermediate ones.
NCERT: Class 12 Physics, Chapter 13