JEE Main & Advanced JEE Main Paper (Held on 10-4-2019 Afternoon)

  • question_answer
    The ratio of the shortest wavelength of two spectral series of hydrogen spectrum is found to be about 9. The spectral series are: [JEE Main 10-4-2019 Afternoon]

    A) Paschen and P fund

    B) Lyman and Paschen

    C) Brackett and Piund

    D) Balmer and Brackett

    Correct Answer: B

    Solution :

    \[\frac{\frac{1}{{{\lambda }_{2}}}={{R}_{H}}\left( \frac{1}{n_{1}^{2}}-\frac{1}{n_{2}^{2}} \right){{Z}^{2}}}{\frac{1}{{{\lambda }_{1}}}={{R}_{H}}\left( \frac{1}{m_{1}^{2}}-\frac{1}{m_{2}^{2}} \right){{Z}^{2}}}\]as for shortest wavelengths both \[{{n}_{2}}\]and \[{{m}_{2}}\]are\[\infty \]           \[\therefore \]\[\frac{{{\lambda }_{1}}}{{{\lambda }_{2}}}=\frac{9}{1}=\frac{m_{1}^{2}}{n_{1}^{2}}\] Now if \[{{m}_{1}}=3\And {{n}_{1}}=1\]it will justify the statement hence Lyman and Paschen is correct.


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