Q.Explain, using the relation between nuclear radius and mass number, why the density of nuclear matter is nearly the same for every nucleus, light or heavy. State its approximate order of magnitude.

A nucleus $^{A}_{Z}X$ is made of $Z$ protons and $N=A-Z$ neutrons, together called nucleons; mass number $A$ = total nucleons, atomic number $Z$ = proton count (fixing the element). Scattering experiments show nuclear radius grows as $R=R_0A^{1/3}$, $R_0\approx1.2\ \text{fm}$, so nuclear volume $\propto A$: every nucleon occupies roughly the same volume, packed together almost like drops of an incompressible nuclear liquid. Because both mass and volume scale with $A$, nuclear density comes out nearly the SAME ($\approx2.3\times10^{17}\ \text{kg/m}^3$) for every nucleus, light or heavy -- a striking feature with no counterpart in ordinary bulk matter.