In a simplified model, both an atom and its nucleus are treated as spheres. If a typical atom has a radius of the order of 10−10 m10^{-10}\text{ m}10−10 m and its nucleus has a radius of the order of 10−15 m10^{-15}\text{ m}10−15 m, what is the typical order of magnitude of the fraction of the atom's volume that is occupied by its nucleus?
10−510^{-5}10−5
10−1010^{-10}10−10
10−1510^{-15}10−15
101510^{15}1015