JEE Main · 2022 · 28 Jul 2022 · Shift 2 · Modern Physics

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A radioactive sample decays to th of its original quantity in 15 minutes. The half-life of the sample is
  1. (A)5 min✓ Correct
  2. (B)7.5 min
  3. (C)15 min
  4. (D)30 min

Answer: (A)

Solution

A sample left with one-eighth of its original amount has halved repeatedly until , which requires since . These three half-lives together take up the given 15 minutes, so each half-life lasts minutes.

JEE Main · 2022 · 28 Jul 2022 · Shift 2 · Single correct option

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