Which graph in the following diagrams correctly represents the potential energy $U$ of a pair of nucleons as a function of their separation $r$?

$1 \, \text{atomic mass unit (amu)}$ is equal to:

Assume that a neutron breaks into a proton and an electron. The energy released during this process is: ............ $MeV$ (mass of neutron $= 1.6725 \times 10^{-27} \ kg$,mass of proton $= 1.6725 \times 10^{-27} \ kg$,mass of electron $= 9 \times 10^{-31} \ kg$).

$A$ nucleus of deuterons or deuterium is a bound atomic system best described by

$A$ heavy nucleus at rest breaks into two fragments which fly off with velocities in the ratio $8 : 1$. The ratio of radii of the fragments is

The density (in $kg m^{-3}$) of nuclear matter is of the order of