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NEET 2016
Exam
NEET
Year
2016
Subject
Physics
Chapter
Nuclear Physics

NEET 2016 · Physics · Nuclear Physics

The half-life of a radioactive substance is 30min . The time (in...

The half-life of a radioactive substance is 30min30min. The time (in minutes) taken between 4040 % decay and 8585 % decay of the same radioactive substance is

Options

  1. A1515
  2. B3030
  3. C4545
  4. D6060

Correct answer

D. 6060

Step-by-step solution

Number of active nuclei falls from 60% to 15%

So the sample becomes 14th\dfrac{1}{4}th

=122th= \dfrac{1}{{2}^{2}}th

So the number of half-lives = 2

Time t=2×30=60mint = 2 \times 30 = 60min
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