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JEE Main 2020 (3 Sep, Shift 1) · Law of Radioactive Decay

Law of Radioactive Decay question from JEE Main 2020 (3 Sep, Shift 1)

Q74JEE Main 2020 · 3 SEP · SHIFT 1Medium

Law of Radioactive Decay

In a radioactive material, fraction of active material remaining after time t is 9/16. The fraction that was remaining after t/2 is

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Answer: (a)

$\frac{N}{N_0} = e^{-\lambda t} = \frac{9}{16}$ .
After $t/2$ : $e^{-\lambda t/2} = \sqrt{\frac{9}{16}} = \frac{3}{4}$ .
So the answer is (a) $\frac{3}{4}$ .

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