(a) N/Z ratio inside a nucleus is responsible for stability of a nucleus.
(b) It must be greater than or equal to unity and less than 1.6
(c) Reason for N/Z ratio to be greater than unity is due to the fact that protons are positively charged and repel on another electrically. This repulsion becomes so great in nuclei with more than 10 protons or so that an excess of neutrons, which produce only attractive nuclear forces, is required for stability. Thus N/Z ratio increases with increase in Z.
(d) When excess of neutrons or protons in a nuclide is there then the nuclide α-decay or β-decay to achieve the required N/Z ratio for stability. This causes radioactive disintegrations of nuclides.
