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

  • question_answer
    The half-life period of a radioactive substance is 5 min. The amount of substance decayed in 20 min will be [MP PMT/PET 1998]

    A)            93.75%                                    

    B)            75%

    C)            25%                                          

    D)            6.25%

    Correct Answer: A

    Solution :

                       Number of half lives in 20 min = n \[=\frac{20}{5}=4\] Fraction of material remains after four half lives \[=\frac{1}{16}\] Hence fraction that decays \[=1-\frac{1}{16}=\frac{15}{16}=93.75%\]


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