DUMET Medical DUMET Medical Solved Paper-2006

  • question_answer
    The radius of germanium (Ge) nuclide is measured to be twice the radius of \[_{4}^{9}\]Be. The number of nucleons in Ge are :

    A)  73             

    B)  74

    C)  75             

    D)  72

    Correct Answer: D

    Solution :

     Let radius of \[_{4}^{9}\]Be nucleus be r. Then, radius of germanium (Ge) nucleus will be 2r. Radius of a nucleus is given by \[R={{R}_{0}}\,{{A}^{1/3}}\] \[\therefore \] \[\frac{{{R}_{1}}}{{{R}_{2}}}={{\left( \frac{{{A}_{1}}}{{{A}_{2}}} \right)}^{1/3}}\] \[\Rightarrow \] \[\frac{r}{2r}={{\left( \frac{9}{{{A}_{2}}} \right)}^{1/3}}\] \[(\because \,\,{{A}_{1}}=9)\] \[\Rightarrow \] \[{{\left( \frac{1}{2} \right)}^{3}}=\frac{9}{{{A}_{2}}}\] Hence, \[{{A}_{2}}=9\times {{(2)}^{3}}\] \[=9\times 8\] = 72 Thus, in germanium (Ge) nucleus, number of nucleons is 72.


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