Question

If $M(A ; Z), M_{p}$ and $M_{n}$ denote the masses of the nucleus ${ }_{Z}^{A} X$, proton and neutron respectively in units of $u \left(1 u =931.5 \,MeV / c ^{2}\right)$ and $B E$ represents its bonding energy in $MeV$, then

• A. $M(A, Z)=Z_{p}+(A-Z) M_{n}-B E$
• B. $M(A, Z)=Z M-p+(A-Z) M_{n}+B E / c^{2}$
• C. $M(A, Z)=Z M_{p}+(A-Z) M_{n}-B E / c^{2}$
• D. $M(A, Z)=Z M_{p}+(A-Z) M_{n}+B E$

Answer 1

Answer: (C)

$Z M_{p}+(A-Z) M_{n}-M(A, Z)$
$=$ mass effect $=\frac{B \cdot E}{c^{2}}$
$\Rightarrow M(A, Z)=Z M_{p}+(A-Z) M_{n}-\frac{B \cdot E}{c^{2}}$