A freshly prepared radioactive source of half-life 2 h, emits radiations of intensity which is 64 ti — Nuclear Chemistry and Radioactivity Chemistry Question

💡 Solution & Explanation

The activity needs to fall to $1/64$ of its initial value. Since $1/64 = (1/2)^6$, this requires exactly 6 half-lives. Minimum safe time = $6 \times t_{1/2} = 6 \times 2 \text{ h} = 12 \text{ h}$. Therefore, correct answer is B.