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JEE Main & Advanced Sample Paper JEE Main Sample Paper-42

  • question_answer
    A radioactive sample whose half-life is 40 h has 18 times too much activity for safety, then after how many half-lives will the radioactive sample will be safe?        

    A)  4                                

    B)  5

    C)  40                              

    D)  1

    Correct Answer: B

    Solution :

    Safe activity is \[<\frac{{{R}_{0}}}{18}\]As\[\frac{{{R}_{0}}}{32}<\frac{{{R}_{0}}}{18}<\frac{{{R}_{0}}}{16}\] So, number of half-lives in which sample becomes safe is 5.


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