What kind of force exists between two neutrons?

The ratio of the nuclear radii of elements with mass numbers $216$ and $125$ is

$A$ nucleus has mass number $\alpha$ and radius $R_{\alpha}$. Another nucleus has mass number $\beta$ and radius $R_{\beta}$. If $\beta = 8\alpha$,then $R_{\alpha}/R_{\beta}$ is:

What is the ratio of $\frac{q}{m}$ for an $\alpha$-particle to that of a proton?

What is the nucleus of an atom?

The nuclear reaction is represented by $X(n, \alpha) \to _3^7Li$. Which element is $X$?