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

  • question_answer
    A radio isotope has a half life of 75 years. The fraction of the atoms of this material that would decay in 150 years will be                   [BHU 1997]

    A)            66.6%                                      

    B)            85.5%

    C)            62.5%                                      

    D)            75%

    Correct Answer: D

    Solution :

                       Number of half lives in 150 years \[n=\frac{150}{75}=2\] Fraction of the atom of decayed \[=1-{{\left( \frac{1}{2} \right)}^{n}}\] \[=1-{{\left( \frac{1}{2} \right)}^{2}}=\frac{3}{4}=0.75\] Þ Percentage decay = 75%


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