Experiments show that all nuclei are approximately spherical with radius that increases as $A^{\frac{1}{3}}.$ The $q,$ of a sphere is proportional to radius cubed, thus is proportional to the number of nucleons $($ since $(A^{\frac{1}{3}}{)}^3=A).$ This means the $q,$ of any nucleus is about the same. This is consistent with a short$-$range attractive nuclear force since there is no apparent tendency for the nucleons to be drawn closer together with increasing nucleus size.

diameter; cross$-$sectional area

surface area; size

angular momentum; total spin

volume; density