Question

In an $\alpha$-decay, the Kinetic energy of $\alpha$ particle is $48\text{MeV}$ and Q-value of the reaction is $50\text{MeV}$. The mass number of the mother nucleus is :
(Assume that daughter nucleus is in ground state)

• A. $96$
• B. $100$
• C. $104$
• D. None of these

Answer 1

The correct option is B $100$

$KE$ in $\alpha$ - decay is
$E=\frac{A-4}{A}\times Q$
$48\text{MeV}=\left(\frac{A-4}{A}\right)\times 50\text{MeV}$
$A=100$