Answer:
D. electron < neutron < atomic nucleus < atom
Explanation:
size of an electron = 2.82 * 10^{-15} m.
size of a neutron = 0.8 * 10^{-15} m.
size of a atomic nucleus = 1.56 * 10^{-14} m.
size of an atom = 0.1 - 0.5 nanometers
hence if we compare the size of all components we will see size of an electron is the smallest and size of an atom is the largest.
electron < neutron < atomic nucleus < atom
