If M (A; Z), Mₚ and Mₙ denote the masses of the nucleus AZ X, proton and neutron respectively in units of u (1u = 931.5 MeV/c) and BE represents its bonding energy in MeV, then

Options

(a) M(A, Z) = ZMₚ + (A – Z)Mₙ – BE/c²
(b) M(A, Z) = ZMₚ + (A – Z)Mₙ + BE
(c) M(A, Z) = ZMₚ + (A – Z)Mₙ – BE
(d) M(A, Z) = ZMₚ + (A – Z)Mₙ + BE/c²

Correct Answer:

M(A, Z) = ZMₚ + (A – Z)Mₙ – BE/c²

Explanation:

Mass defect = ZMₚ + (A – Z)Mₙ – M(A – Z)
or, B.E. / c² = ZMₚ + (A – Z)Mₙ – M(A – Z)
M(A – Z) = ZMₚ + (A – Z)Mₙ – B.E. / c²