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NEET Sample Paper NEET Sample Test Paper-85

  • question_answer
    The half-life \[o{{f}^{215}}\] At is\[100\mu s.\] The time taken for the radioactivity of a sample \[o{{f}^{215}}\]At to decay to\[1/{{16}^{th}}\]of its initial value is

    A) \[400\mu s\]      

    B)        \[6.3\mu s\]

    C) \[40\mu s\]        

    D)        \[300\mu s\]

    Correct Answer: A

    Solution :

    [a]        \[N={{N}_{0}}{{\left( \frac{1}{2} \right)}^{n}}\] or         \[\frac{{{N}_{0}}}{16}=\,\,\,\,{{N}_{0}}{{\left( \frac{1}{2} \right)}^{n}}\] or         \[n\,\,\,\,=\,\,\,\,4\] \[t\,\,\,\,=\,\,\,\,n{{t}_{1/2}}=4\times 100=400\,\,\mu s.\]


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