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Physics · PYQ NEET UG 2023
हिन्दीThe half life of a radioactive substance is 20 minutes. In how much time, the activity of substance drops to \( (\frac{1}{16})^{\text{th}} \) of its initial value?
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Correct answer · Option B
80 minutes
Explanation
Activity \( A = A_0 (\frac{1}{2})^{t/T_{1/2}} \). Given \( \frac{A}{A_0} = \frac{1}{16} = (\frac{1}{2})^4 \), so \( \frac{t}{20} = 4 \Rightarrow t = 80\text{ minutes} \).
