$A$ nucleus with mass number $220$ initially at rest emits an $\alpha -$ particle. If the $Q$ value of the reaction is $7.8 \, MeV$ and subsequently after the emission of the $\alpha -$ particle,a photon of energy $1.2 \, MeV$ is also emitted. The kinetic energy of the $\alpha -$ particle is ? .......... $MeV$

How much energy is produced by the fission of $1\, kg$ of uranium?

$A$ star has $10^{40}$ deuterons. It produces energy via the processes:
$_1H^2 + _1H^2 \to _1H^3 + p$
$_1H^2 + _1H^3 \to _2He^4 + n$
If the average power radiated by the star is $10^{16} \ W$, the deuteron supply of the star is exhausted in a time of the order of:
Given:
Mass of $_1H^2 = 2.014 \ amu$
Mass of $_2He^4 = 4.001 \ amu$
Mass of proton = $1.007 \ amu$
Mass of neutron = $1.008 \ amu$

Two lighter nuclei combine to form a comparatively heavier nucleus by the relation given below:
${ }_{1}^{2} X +{ }_{1}^{2} X ={ }_{2}^{4} Y$
The binding energies per nucleon of ${ }_{1}^{2} X$ and ${ }_{2}^{4} Y$ are $1.1 \, MeV$ and $7.6 \, MeV$ respectively. The energy released in this process is in $MeV$.

When a slow neutron goes sufficiently close to a ${U^{235}}$ nucleus,then the process that takes place is

$A$ $\pi^0$ meson at rest decays into $2$ $\gamma$ rays: $\pi^0 \to \gamma + \gamma$. Which of the following must happen?