A freshly prepared radioactive source with a half-life period of emits radiations of intensity which — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

Let the safe intensity level be $I_{safe}$. Initial intensity $I_0 = 64 I_{safe}$. The intensity decreases according to $I = I_0 (1/2)^n$, where $n$ is the number of half-lives. We want $I = I_{safe}$, so $1 = 64 (1/2)^n$, meaning $(1/2)^n = 1/64 = (1/2)^6$. Thus, $n = 6$ half-lives are required. Total time $t = 6 \times 2\text{ hours} = 12\text{ hours}$.