The mass number of a nucleus is equal to the number of

Which of the following is a fundamental force in nature?

If the nuclear forces between two protons,two neutrons,and a proton-neutron are denoted by $F_{pp}$,$F_{nn}$,and $F_{pn}$ respectively,then:

Consider the following two statements, $A$ and $B$ and identify the correct answer given below:
$A$. Nuclear density is same for all nuclei.
$B$. Radius of the nucleus $R$ and its mass number $A$ are related as $\sqrt{A} \propto R^{1 / 6}$.

In the nuclear reaction: $X(n, \alpha) {_3Li^7}$,the term $X$ will be

Which stable nucleus has a radius that is half that of $Fe^{56}$?