$A$ $\gamma$-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:

In an atomic reactor and an atomic bomb,the multiplication factor $(r)$ per fission is respectively:

$A$ $^{235}U$ nuclear reactor generates energy at a rate of $3.70 \times 10^7 \text{ J/s}$. Each fission liberates $185 \text{ MeV}$ of useful energy. If the reactor has to operate for $144 \times 10^4 \text{ s}$, the mass of the fuel needed is (Assume Avogadro's number $= 6 \times 10^{23} \text{ mol}^{-1}$, $1 \text{ eV} = 1.6 \times 10^{-19} \text{ J}$) (in $\text{ kg}$)

The fission of $_{92}^{235}U$ can be triggered by the absorption of a slow neutron by a nucleus. Similarly,a slow proton can also be used. This statement is

Let $E_1$ and $E_2$ be the binding energies of two nuclei $A$ and $B.$ It is observed that two nuclei of $A$ combine together to form a $B$ nucleus. This observation is correct only if

The nucleus of $_6C^{12}$ absorbs a neutron and emits a $\beta$-particle. The resulting nucleus is ........