CMC Medical CMC-Medical VELLORE Solved Paper-2011

  • question_answer
    The one electron species having ionization energy of 54.4 eV is

    A)  \[H\]                                    

    B)  \[H{{e}^{+}}\]

    C)  \[{{B}^{4+}}\]                                  

    D)  \[L{{i}^{2+}}\]

    E)  \[B{{e}^{2+}}\]

    Correct Answer: B

    Solution :

                    \[{{E}_{n}}=\frac{-13.6\times {{(Z)}^{2}}}{{{n}^{2}}}eV\] If             \[n=1\] \[{{E}_{n}}=-13.6\,{{Z}^{2}}\] \[\therefore \]  \[{{Z}^{2}}=\frac{-\,54.4}{-13.6}\]                 \[{{Z}^{2}}=4\]                  \[Z=2\] Thus, the species with atomic number 2 (i.e.,\[H{{e}^{+}}\]) has the ionisation energy 54.4 eV.


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