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

  • question_answer
    Half-life of a substance is 10 years. In what time, it becomes \[\frac{1}{4}\]th part of the initial amount                  [AIEEE 2002]

    A)            5 years                                    

    B)            10 years

    C)            20 years                                 

    D)            None of these

    Correct Answer: C

    Solution :

                       \[N={{N}_{0}}{{e}^{-t/{{T}_{1/2}}}}\Rightarrow \frac{1}{4}={{e}^{-t/10}}\] \[\Rightarrow {{\left( \frac{1}{2} \right)}^{2}}=\frac{1}{{{e}^{t/10}}}\Rightarrow t=20\ years\]


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