Tritium has a half life of 12.5 years against beta decay. What fraction of a sample of pure tritium will remain undecayed after 25 years?

Options

A. one half
B. one fourth
C. one third
D. can't say

Answer

B

Explanation

According to the concept of half life, half of the initial sample will remain undecayed after 12.5 y. In next 12.5 y, one half of these nuclei would decay. Hence one fourth of the initial sample of pure tritium will remain undecayed.