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MHT CET 2021 (20 Sep, Shift 2) · Law of Radioactive Decay

Law of Radioactive Decay question from MHT CET 2021 (20 Sep, Shift 2)

Q52MHT CET 2021 · 20 SEP · SHIFT 2Easy

Law of Radioactive Decay

A sample of radioactive element contains $8 \times 10^{16}$ active nuclei. The halt-life of the element is 15 days. The number of nuclei decayed after 60 days is

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Answer: (a)

$n = \frac{60}{15} = 4$ half-lives.
Remaining $N = \frac{8 \times 10^{16}}{2^4} = 0.5 \times 10^{16}$ .
Decayed $= 8 \times 10^{16} - 0.5 \times 10^{16} = 7.5 \times 10^{16}$ .
So the answer is (a) $7.5 \times 10^{16}$ .

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