Q 12-13-018NEETJEE MainMedium
The activity of a radioactive sample falls to $\dfrac{1}{8}$ of its initial value in $24$ hours. Its half-life is
Answer: (A) $8$ h
Concept. Activity halves every half-life.
Step 1. Number of half-lives. $\dfrac18 = \left(\dfrac12\right)^3$: three half-lives.
Step 2. Half-life. $T_{1/2} = \dfrac{24}{3} = 8$ h.
Answer. $8$ h (Option A).
Solution by Sreeraj P, M.Sc Physics