A nucleus has mass number A _ 1 and volume V _ 1 . Another nucleus...

For a nucleus we can write volume: $V = \dfrac{4}{3}\pi{R}^{3}$

Now, $R = {R}_{0}\left(A\right)\dfrac{1}{3}$

Therefore, $V = \dfrac{4}{3}\pi{R}_{0}^{3}A$

$⇒ \dfrac{{V}_{2}}{{V}_{1}} = \dfrac{{A}_{2}}{{A}_{1}} = 4$