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The binding energy per nucleon is almost constant for the nuclei having atomic mass number ______.

Asked in GSEB Board March 2020 · Binding energy curve and nuclear force

Answer: (2) 30<A<170

Step-by-step solution

Idea: read the shape of the binding-energy-per-nucleon curve. It climbs steeply for the lightest nuclei, levels off near 8.5 MeV per nucleon, and then falls slowly.

The level stretch runs from about A=30 to about A=170; across it E_bn stays within a few per cent of 8 MeV, because the short-range nuclear force lets each nucleon feel only its neighbours however big the nucleus gets.

Beyond A=170 the long-range Coulomb repulsion between the many protons pulls the curve down.

So the binding energy per nucleon is almost constant for 30<A<170.

Why the other options are wrong

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