A nucleus ZXA has mass represented by M(A, Z). If Mp and

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A nucleus _ZX^A has mass represented by M(A, Z). If M_p and M_n denote the mass of proton and neutron respectively and B.E. the binding energy in MeV, then

1. B.E. = [ZM_p + (A – Z)M_p – M(A, Z)]c²
2. B.E. = [ZM_p + ZMn – M(A, Z)]c²
3. B.E. = M(A, Z) – ZM_p – (A – Z)M_n
4. B.E. = [M(A, Z) – ZM_p – (A – Z)M_n]c²

Correct Option: A

The difference in mass of a nucleus and its constituents, ΔM, is called the mass defect and is given by
ΔM = [ZM_p + (A - Z)M_n] - M
and binding energy = ΔMc²
[{ZM_p + (A - Z)M_n} - M]c²