Write the relation of the size of the nucleus to the atomic size.

(N/A) The radius of the nucleus $R$ is given by the relation $R = R_0 A^{1/3}$, where $R_0 \approx 1.2 \times 10^{-15} \ m$ and $A$ is the mass number.
The size of the nucleus is of the order of $10^{-15} \ m$ (femtometer).
The size of an atom is of the order of $10^{-10} \ m$ ($\mathring{A}$).
Therefore, the ratio of the size of the nucleus to the atomic size is approximately $10^{-15} / 10^{-10} = 10^{-5}$.
This indicates that the nucleus is about $10^5$ times smaller than the atom.