One of the fusion reactions in the sun is given by ${ }_{1}^{2} H+{ }_{1}^{1} H \rightarrow{ }_{2}^{3} He+\gamma+Q$. Calculate the energy $Q$ released in the reaction. (in $MeV$)

Pick out the correct statements from the following:
$I$. Electron emission during $\beta$-decay is always accompanied by neutrino.
$II$. Nuclear force is charge independent.
$III$. Fusion is the chief source of stellar energy.

$A$ $\gamma$-ray photon creates an electron-positron pair. If the rest mass energy of an electron is $0.51 \, MeV$ and the total kinetic energy of the electron-positron pair is $0.78 \, MeV$,then the energy of the $\gamma$-ray photon in $MeV$ is:

The energy liberated on complete fission of $1\, kg$ of $_{92}{U^{235}}$ is (Assume $200\, MeV$ energy is liberated on fission of $1$ nucleus).

The energy released by the fission of one uranium atom is $200 \text{ MeV}$. The number of fissions per second required to produce $6.4 \text{ W}$ power is $\qquad$ .

The energy liberated per nuclear fission is $200 \; MeV$. If $10^{20}$ fissions occur per second,the amount of power produced will be: