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JEE Main & Advanced Chemistry Surface & Nuclear Chemistry / भूतल और नाभिकीय रसायन Question Bank Artificial Transmutation

  • question_answer
    A radioactive isotope has a half-life of 20 days. If 100 gm of the substance is taken, the weight of the isotope remaining after 40 days is                                  [NCERT 1979]

    A)                 25 gm   

    B)                 2.5 gm

    C)                 60 gm   

    D)                 40 gm

    Correct Answer: A

    Solution :

               \[n=\frac{40}{20}=2\]                                 \[\therefore \] Amount left \[\frac{{{N}_{0}}}{{{2}^{n}}}=\frac{100}{{{2}^{2}}}=25gm\]


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