JEE Main & Advanced Physics Nuclear Physics And Radioactivity Question Bank Self Evaluation Test - Nuclei

  • question_answer
    If a radioactive material contains 0.1 mg of \[T{{h}^{234}}\]how much of it will remain unchanged after 120 days. Given Half-life is 24 days

    A)  \[1.12\text{ }\mu g\]  

    B)  \[0.1\text{ }\mu g\]

    C)  \[3.125\text{ }\mu g\]

    D)  \[125\text{ }\mu \text{g}.\]

    Correct Answer: C

    Solution :

    [c] Using \[\frac{M}{{{M}_{0}}}={{\left( \frac{1}{2} \right)}^{t/T}}={{\left( \frac{1}{2} \right)}^{120/24}}={{\left( \frac{1}{2} \right)}^{5}}=\frac{1}{32}\] So \[M=\frac{{{M}_{0}}}{32}=\frac{0.1mg}{32}=3.125\,\mu g.\]


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