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JEE Main & Advanced Sample Paper JEE Main Sample Paper-8

  • question_answer
    The activity of a radioactive substance drops to 1/32 of its initial value in 7.5 h. Find the half life.

    A)  2 hours                               

    B)  1.5 hours

    C)   1 hours                              

    D)  2.5 hours

    Correct Answer: B

    Solution :

     Using \[\frac{A}{{{A}_{0}}}={{\left( \frac{1}{2} \right)}^{t/T}}\]or \[\frac{1}{32}={{\left( \frac{1}{2} \right)}^{7.5/T}}\] or \[{{\left( \frac{1}{2} \right)}^{5}}={{\left( \frac{1}{2} \right)}^{7.5/T}}\]or \[5=\frac{7.5}{T}\]i.e., T = 1.5 hours


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