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JEE Main 2022 (27 Jul, Shift 2) · Law of Radioactive Decay

Law of Radioactive Decay question from JEE Main 2022 (27 Jul, Shift 2)

Q43JEE Main 2022 · 27 JUL · SHIFT 2Easy

Law of Radioactive Decay

The activity of a radioactive material is 6.4×10−46.4 \times 10^{-4} curie. Its half life is 5 days. The activity will become 5×10−65 \times 10^{-6} curie after:

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Answer: (d)

  1. A0A=6.4×10−45×10−6=128=27\frac{A_0}{A} = \frac{6.4 \times 10^{-4}}{5 \times 10^{-6}} = 128 = 2^7, so 7 half-lives.
  2. t=7×5=35t = 7 \times 5 = 35 days.
  3. So the answer is (d) 35 days.
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