CMC Medical CMC-Medical VELLORE Solved Paper-2015

  • question_answer
    Radioactive equilibrium is established in a uranium mineral between radium and 1 uranium atom in the 1:28 ratio. If \[\frac{1}{2}\] period of radium is 1620 yr, calculate the disintegration constant of uranium.

    A)  \[1.43047\times {{10}^{12}}{{s}^{-1}}\]

    B)  \[4.844\times {{10}^{-13}}{{s}^{-1}}\]

    C)  \[4.844\times {{10}^{+13}}s\]

    D)  \[1.43047\times {{10}^{-12}}{{s}^{-1}}\]

    E)  \[1.43047\times {{10}^{+12}}{{s}^{-1}}\]

    Correct Answer: B

    Solution :

                    We have        \[\underset{Radium\,}{\mathop{{{N}_{1}}{{\lambda }_{1}}}}\,=\underset{Uranium}{\mathop{{{N}_{2}}{{\lambda }_{2}}}}\,\] \[\frac{{{\lambda }_{1}}}{{{\lambda }_{2}}}=\frac{{{N}_{2}}}{{{N}_{1}}}=\frac{28}{1}\]     \[\frac{{{\left( \frac{0.693}{{{t}_{50}}} \right)}_{1}}}{{{\left( \frac{0.693}{{{t}_{50}}} \right)}_{52}}}=\frac{{{({{t}_{50}})}_{2}}}{{{({{t}_{50}})}_{1}}}=\frac{28}{1}\] \[{{({{t}_{50}})}_{2}}=1620\times 28\,yr=1.43047\times {{10}^{12}}s\] \[{{\lambda }_{2}}=\frac{0.693}{{{t}_{50}}}=4.844\times {{10}^{-13}}{{s}^{-1}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner