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NEET Sample Paper NEET Sample Test Paper-59

  • question_answer
    The wavelength of the first line of Lyman series for hydrogen atom is equal to that of the second line of Balmer series for a hydrogen like ion. The atomic number Z of hydrogen like ion is:

    A) 4                                 

    B) 1     

    C) 2                                 

    D) 3

    Correct Answer: C

    Solution :

    [c] Wavelength of the first line of lyman series for hydrogen atom is (Z=1) \[\frac{1}{\lambda }=R\left[ \frac{1}{{{(1)}^{2}}}-\frac{1}{{{(2)}^{2}}} \right]=\frac{3R{{Z}^{2}}}{16}\Rightarrow {{\lambda }^{''}}=\frac{16}{3R{{Z}^{2}}}\] \[\lambda ''=\lambda \] \[\frac{16}{3R{{Z}^{2}}}=\frac{4}{3R}\Rightarrow Z=2\] Note In such question, sometimes we have use term \[\frac{1}{R}=911\,\overset{o}{\mathop{A}}\,\]


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