Answer:
Option B. Coulomb Repulsion
Explanation:
The reason for the heavy nucleus not being able to follow the trend or the N= Z line is because of the fact that as the atomic number, Z of an atom increases, the number of protons inside the atom also increases. Since the neutrons are charge less particles whereas the protons are positively charged particle and hence as these increases in number there is an increase in the repulsive force between the like charges, i.e., positively charged protons which is Coulomb repulsion.
