Q 12-13-092JEE MainJEE Main 2022 (27 Jul, Shift 1)Easy
What is the half-life period of a radioactive material if its activity drops to $\dfrac{1}{16}$th of its initial value of $30$ years ?
Answer: (C) $7.5$ years
$\dfrac{1}{16} = \left(\dfrac12\right)^4$, so $30$ years is $4$ half-lives:
$$T_{1/2} = \frac{30}{4} = 7.5\ \text{years}$$
Solution by Sreeraj P, M.Sc Physics