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JEE Main & Advanced Physics Nuclear Physics And Radioactivity Question Bank Radioactivity

  • question_answer
    If half-life of a substance is 3.8 days and its quantity is 10.38 gm. Then substance quantity remaining left after 19 days will be                                                         [RPMT 2000; AFMC 2002]

    A)            0.151 gm                                

    B)            0.32 gm

    C)            1.51 gm                                  

    D)            0.16 gm

    Correct Answer: B

    Solution :

                       Number of half lives \[n=\frac{19}{3.8}=5;\]Now \[\frac{N}{{{N}_{0}}}={{\left( \frac{1}{2} \right)}^{n}}\] \[\Rightarrow \frac{N}{10.38}={{\left( \frac{1}{2} \right)}^{5}}\Rightarrow N=10.38\times {{\left( \frac{1}{2} \right)}^{5}}\]\[=0.32gm\]


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