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NEET Sample Paper NEET Sample Test Paper-30

  • question_answer
    A radiactive isotope having a half life of \[2.3\]days was received after \[9.2\]days. It was found that there were 300 mg of the isotope in the container. The initial amount of the isotope was:                   

    A)  1200 mg        

    B)  3600mg

    C)  4800 mg        

    D)  2400mg              

    Correct Answer: D

    Solution :

    \[T=n\times {{t}_{{\scriptstyle{}^{1}/{}_{2}}}}\] \[n=\frac{T}{{{t}_{{\scriptstyle{}^{1}/{}_{2}}}}}=\frac{9.2}{2.3}=4\] \[\frac{N}{{{N}_{0}}}={{\left( \frac{1}{2} \right)}^{n}}\] \[\frac{300}{{{N}_{0}}}={{\left( \frac{1}{2} \right)}^{4}}=\frac{1}{8}\] \[{{N}_{0}}=300\times 8=2400\,mg\] 


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