BCECE Engineering BCECE Engineering Solved Paper-2003

  • question_answer
    In hydrogen atom when an electron jumps from second to first orbit, the wavelength of line emitted is :     

    A)  \[0.563\,\overset{\text{o}}{\mathop{\text{A}}}\,\]                                       

    B)         \[4861\,\overset{\text{o}}{\mathop{\text{A}}}\,\]

    C)         \[4102\,\overset{\text{o}}{\mathop{\text{A}}}\,\]                        

    D)         \[1213\,\overset{\text{o}}{\mathop{\text{A}}}\,\]

    Correct Answer: D

    Solution :

    For ionization energy of electron in nth orbit               \[{{E}_{n}}=\frac{-13.6}{{{n}^{2}}}eV\] For an electron in Ist orbit, i.e.,\[n=1\]                     \[{{E}_{1}}=\frac{-13.6}{{{1}^{2}}}=-13.6\,eV\] For an electron in \[\text{II}\,\text{nd}\]orbit, i.e.,\[~n=2\]                 \[{{E}_{2}}=\frac{-13.6}{{{2}^{2}}}=-3.4\,eV\] Therefore, energy released \[\Delta E={{E}_{2}}-{{E}_{1e}}\] \[=(-3.4)-(-13.6)\] \[=10.2\,eV\] Therefore, wavelength of line emitted is given by \[\lambda =\frac{12375}{\Delta E}\overset{\text{o}}{\mathop{\text{A}}}\,\] \[=\frac{12375}{10.2}\overset{\text{o}}{\mathop{\text{A}}}\,\] \[=1213\overset{\text{o}}{\mathop{\text{A}}}\,\]


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