Isotopes with the lowest possible n/p ratio are usually the most stable.

Question

Quizplus · Accepted Answer

Isotopes with a low neutron-to-proton (n/p) ratio typically have fewer neutrons than protons, which means that the strong nuclear force has an easier time holding the nucleus together. As a result, isotopes with low n/p ratios tend to be more stable than those with higher ratios. However, there is a limit to how low the n/p ratio can be before the nucleus becomes too proton-rich and starts to decay.

Isotopes with the Lowest Possible N/p Ratio Are Usually the Most