Given:
Radius of atom, ra = 1 Å = 10-10 m
Radius of nucleus, rn = 1 fermi = 10-15 m
Volume of atom; \(V_1 = \frac{4}{3}\pi r^3_a\)
Volume of nucleus,\(V_2 = \frac{4}{3}\pi r^3_n\)
\(\frac{V_1}{V_2}\,=\,\frac{\frac{4}{3}\pi r^3}{\frac{4}{3}\pi r_n^3}\,=\,(\frac{r_a}{r_n})^3\,=\,(\frac{10^{-10}}{10^{-15}})^3\,=10^{15}\)