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NEET NEET SOLVED PAPER 2016 Phase-II

  • question_answer
    The half-life of a radioactive substance is 30 minutes. The time (in minutes) taken between 40% decay and 85% decay of the same radioactive substance is

    A)  15                               

    B)  30

    C)  45                               

    D)  60

    Correct Answer: D

    Solution :

    Number of active nuclei falls from 60% to 15% So sample becomes \[\frac{1}{4}th\] \[=\frac{1}{{{2}^{2}}}th\] So number of half-lives = 2 Time \[t=2\times 30=60\]minute


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