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

  • question_answer
    The half-life of radioactive Polonium (Po) is 138.6 days. For ten lakh Polonium atoms, the number of disintegrations in 24 hours is                                                      [Roorkee 1999]

    A)            2000                                         

    B)            3000

    C)            4000                                         

    D)            5000

    Correct Answer: D

    Solution :

               \[n=\frac{24}{24\times 138.6}=\frac{1}{138.6};\] Now\[\frac{N}{{{N}_{0}}}={{\left( \frac{1}{2} \right)}^{n}}={{\left( \frac{1}{2} \right)}^{1/138.6}}\]                    \[\Rightarrow N=10,00000{{\left( \frac{1}{2} \right)}^{1/138.6}}=995011\]                    So number of disintegration                    \[=1000000-995011=4989\approx 5000\].


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