Question

Nuclei X decay into nuclei Y by emitting $\alpha$ particles. Energies of $\alpha$ particle are found to be only $1$ & $1.4$ MeV. Disregarding the recoil of nuclei Y. The energy of $\gamma$ photon emitted will be?

• A. $0.8$ MeV
• B. $1.4$ MeV
• C. $1$ MeV
• D. $0.4$ MeV

Answer 1

The correct option is D $0.4$ MeV

$\begin{array}{c}\text{Energy of r photon = Difference in energies of alpha particles}\\ \text{Energy of r photon}=(1.4-1)\text{Mey}\\ =0.4Mev\end{array}$