Why is the density of nucleus is more than that of the atom? Show that the density of nuclear matter is same for all nuclei

The binding energy per nucleon in deuterium and helium are $1.1 \mathrm{MeV}$ and $7.0 \mathrm{MeV}$respectively. What energy in joules will be liberated, When$10{ }^6$ deuterons take part in the reaction.

Consider the fission of ${}_{92}{}^{238}\mathrm{U}$ by fast neutrons. In one fission event, no neutrons are emitted and the final end products, after the beta decay of the primary fragments, are ${}_{58}{}^{140}\mathrm{C}\mathrm{e}$ and ${}_{44}{}^{99}\mathrm{R}\mathrm{U}$. Calculate $\mathrm{Q}$ for this fission process. The relevant atomic and particle masses are:
$\mathrm{m}\left({}_{92}{}^{238}\mathrm{U}\right)=238.05079 \mathrm{u}$
$\mathrm{m}\left({}_{58}{}^{140}\mathrm{C}\mathrm{e}\right)=139.90543 \mathrm{u}$
$\mathrm{m}\left({}_{44}{}^{99}\mathrm{R}\mathrm{U}\right)=98.90594 \mathrm{u}$