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

  • question_answer
    A radioactive sample has half-life of 5 years. Probability of decay in 10 years will be                          [RPET 2000]

    A)            100%                                       

    B)            75%

    C)            50%                                          

    D)            25%

    Correct Answer: B

    Solution :

                       Number of half lives \[n=\frac{10}{5}=2,\]now \[\frac{N}{{{N}_{0}}}={{\left( \frac{1}{2} \right)}^{2}}=\frac{1}{4}\]                    Fraction decayed \[=1-\frac{N}{{{N}_{0}}}=1-\frac{1}{4}=\frac{3}{4}\]            Þ In percentage \[=\frac{3}{4}\times 100=75%\]


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