Q 12-13-105JEE MainJEE Main 2021 (20 Jul, Shift 2)Easy
A radioactive substance decays to $\left(\frac{1}{16}\right)^{\text{th}}$ of its initial activity in 80 days. The half life of the radioactive substance expressed in days is ______.
Numerical value type. Enter your answer.
Answer: 20
$\frac{1}{16} = \left(\frac12\right)^4$, so 4 half-lives take 80 days: $T_{1/2} = 20$ days.
Solution by Sreeraj P, M.Sc Physics