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

  • question_answer
    At radioactive equilibrium, the ratio between the atoms of two radioactive elements (X) and (Y)  as found to be \[3.2\times {{10}^{9}}:1\] respectively If half-life of the element  is \[1.6\times {{10}^{10}}\] years, then half-life of the element W would be

    A)  \[3.2\times {{10}^{9}}years\]

    B)  \[5\times {{10}^{9}}years\]

    C)  \[1.6\times {{10}^{10}}years\]

    D)  5 years

    Correct Answer: D

    Solution :

    [d] \[X\xrightarrow{{{\lambda }_{1}}}Y\xrightarrow{{{\lambda }_{2}}}Z\] At radioactive equilibrium, \[({{\lambda }_{X}})\times ({{N}_{X}})=({{\lambda }_{Y}})\times ({{N}_{Y}})\] \[\frac{{{\lambda }_{X}}}{{{\lambda }_{Y}}}=\frac{{{N}_{Y}}}{{{N}_{X}}}\,\,\frac{{{({{t}_{1/2}})}_{Y}}}{{{({{t}_{1/2}})}_{X}}}=\frac{{{N}_{Y}}}{{{N}_{X}}}\]   or    \[\frac{{{({{t}_{1/2}})}_{Y}}}{1.6\times {{10}^{10}}}\] \[=\frac{1}{3.2\times {{10}^{9}}}{{({{t}_{1/2}})}_{Y}}=5\,\,years\]


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