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NEET Sample Paper NEET Sample Test Paper-90

  • question_answer
    One of the lines in the emission spectrum of \[L{{i}^{2+}}\] has the same wavelength as that of the \[{{2}^{nd}}\] line of Balmer series in hydrogen spectrum. The electronic transition corresponding to this line is \[n=12\to n=x.\] Find the value of x.

    A) 8         

    B)                    6

    C) 7                     

    D)         5

    Correct Answer: B

    Solution :

         [b] For \[{{2}^{nd}}\] line of Balmer series in hydrogen spectrum \[\frac{1}{\lambda }=R(1)\left( \frac{1}{{{2}^{2}}}-\frac{1}{{{4}^{2}}} \right)=\frac{3}{16}R\] For \[L{{i}^{2+}}\left[ \frac{1}{\lambda }=R\times 9\left( \frac{1}{{{x}^{2}}}-\frac{1}{{{12}^{2}}} \right)=\frac{3R}{16} \right]\] which is satisfied by \[n=12\to n=6.\]


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