Unstable nuclei attain stability through disintegration. The nuclear stability is related to neutron proton ratio `(n//p)`. For stable nuclei `n//p` ratio lies close to unity for elements with low atmoic numbers (20 or less) but it is more than 1 for nuclei having higher atomic numbers. Nuclei having `n//p` ratio either very high or low undergo nuclear transformation. When `n//p` ratio is higher than required for stability, the nuclei have the tendency to emit `beta`-rays. while when `n//p` ratio is lower than required for stability, the nuclei either emits `alpha`-particles or a positron or capture `K`-electron.
Unstalbe substance exhibit high radioactivity due to a)Low `p//n` ratio b)high `p//n` ratio c)`p//n = 1` d)None

Answer

B