NEET AIPMT SOLVED PAPER 2001

  • question_answer
                    Half-life period of a radioactive substance is 6h. After 24 h activity is 0.01\[\mu \]C, what was the initial activity?

    A)                                                                                                                                                                                            0.04 \[\mu \]C  

    B)                 0.08 \[\mu \]C  

    C)                 0.24 \[\mu \]C  

    D)                 0.16 \[\mu \]C

    Correct Answer: D

    Solution :

                    The activity of a radioactive substance is                 \[R={{R}_{0}}\,{{\left( \frac{1}{2} \right)}^{n}}\]                 Here, n = number of half-lives                 \[=\frac{t}{{{T}_{1/2}}}=\frac{24}{6}=4\]                 \[R=0.01\,\mu C\]                 Hence,                 \[0.01={{R}_{0}}{{\left( \frac{1}{2} \right)}^{4}}\]                         \[or{{R}_{0}}=0.01\times {{(2)}^{4}}\]                 \[=0.01\times 16=0.16\,\mu C\]


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