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JEE Main & Advanced Chemistry Surface & Nuclear Chemistry / भूतल और नाभिकीय रसायन Question Bank Rate of decay and Half-life

  • question_answer
    The half-life of the radio element  \[_{83}B{{i}^{210}}\] is 5 days. Starting with 20 g of this isotope, the amount remaining after 15 days is                                  [BHU 1987]

    A)                 10 g       

    B)                 5 g

    C)                 2.5 g      

    D)                 6.66 g

    Correct Answer: C

    Solution :

              \[n=\frac{15}{5}=3,N=\frac{{{N}_{o}}}{{{2}^{n}}}=\frac{20}{{{2}^{3}}}=\frac{20}{8}=2.5gm.\]


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