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NEET 2001 (AIPMT) · Law of Radioactive Decay

Law of Radioactive Decay question from NEET 2001 (AIPMT)

Q117NEET 2001 · AIPMTEasy

Law of Radioactive Decay

Half life of a radioactive element is 12.5 hour and its quantity is 256 g. After how much time its quantity will remain 1 g?

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Answer: (b)

$\frac{1}{256} = \left(\frac{1}{2}\right)^8$ , so 8 half-lives.
$t = 8 \times 12.5 = 100\text{ h}$ .
So the answer is (b) 100 hrs.

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