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

  • question_answer
    1 mg gold undergoes decay with 2.7 days half-life period, amount left after 8.1 days is [UPSEAT 2001]

    A)            0.91 mg                                  

    B)            0.25 mg

    C)            0.5 mg                                    

    D)            0.125 mg

    Correct Answer: D

    Solution :

                       \[N={{N}_{0}}{{\left( \frac{1}{2} \right)}^{n}}\Rightarrow N={{N}_{0}}{{\left( \frac{1}{2} \right)}^{t/{{T}_{1/2}}}}\] \[\Rightarrow N=1\times {{\left( \frac{1}{2} \right)}^{\frac{8.1}{2.7}}}={{\left( \frac{1}{2} \right)}^{3}}=\frac{1}{8}\]\[\Rightarrow N=\frac{1}{8}mg=0.125\ mg\]


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