Manipal Engineering Manipal Engineering Solved Paper-2012

  • question_answer
    The radius of the smallest electron orbit in hydrogen-like ion is\[(0.51\times {{10}^{-10}}/4)m\], then it is

    A)  hydrogen atom               

    B) \[H{{e}^{+}}\]

    C) \[L{{i}^{2+}}\]                   

    D)        \[B{{e}^{3+}}\]

    Correct Answer: D

    Solution :

    For hydrogen like atom, the radius of nth orbit                 \[r_{n}^{Z}=\frac{{{n}^{2}}}{Z}{{a}_{0}}\] Here,     \[{{a}_{0}}=0.51\times {{10}^{-10}}m\] \[\therefore \]  \[r_{n}^{Z}=\frac{0.51\times {{10}^{-10}}}{4}m\] In the ground state,\[n=1\] \[\therefore \]  \[\frac{0.51\times {{10}^{-10}}}{4}=\frac{{{1}^{2}}}{Z}\times 0.51\times {{10}^{-10}}\] \[\therefore \]  \[Z=4\] So, the atom is triply ionized beryllium\[(B{{e}^{3+}})\].


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