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

  • question_answer
    The half-life of radium is about 1600 years. Of 100 g of radium existing now, 25 g will remain unchanged after [CBSE PMT 2004]

    A)            2400 years                             

    B)            3200 years

    C)            4800 years                             

    D)            6400 years

    Correct Answer: B

    Solution :

               \[M={{M}_{0}}{{\left( \frac{1}{2} \right)}^{\frac{t}{{{T}_{1/2}}}}}\]\[\Rightarrow 25=100{{\left( \frac{1}{2} \right)}^{\frac{t}{1600}}}\]Þ t= 3200 years.


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