Who discovered the neutron?

The ratio of the volume of an $Al^{27}$ nucleus to its surface area is (Given,$R_0 = 1.2 \times 10^{-15} \ m$):

What is the particle $x$ in the following nuclear reaction :
${ }_4^9 Be+{ }_2^4 He \rightarrow{ }_6^{12} C+x$

For a uranium nucleus, how does its mass vary with volume?

$A$ nucleus has mass number $A_1$ and volume $V_1$. Another nucleus has mass number $A_2$ and volume $V_2$. If the relation between mass numbers is $A_2 = 4 A_1$,then $\frac{V_2}{V_1} = $ . . . . . . .

Define nuclear force.