What is the nucleus of an atom ?

Mention the total charge of electron in the atom.

If the nuclear force between two protons, two neutrons and between proton and neutron is denoted by $F _{p p}, F _{n n}$ and $F _{p n}$ respectively, then

Write the unit of mass and its definition.

The deuteron is bound by nuclear forces just as $H-$ atom is made up of $p$ and $e$ bound by electrostatic forces. If we consider the force between neutron and proton in deuteron as given 1 e 2 in the form of a Coulomb potential but with an effective charge $e' \,:\,F = \frac{1}{{4\pi { \in _0}}}\frac{{e{'^2}}}{r}$ . estimate the value of $(e'/e)$ given that the binding energy of a deuteron is $2.2\, MeV.$