Q10 / 125 · BITSAT 2020 · Chemistry

What is the maximum wavelength line in the Lyman series of $\mathrm{He}^{+}$ ion?

  • A
    $3 R$
  • B
    $\frac{1}{\mathrm{R}}$
  • Correct answer
    C
    $\frac{1}{3 R}$
  • D
    None of these

Solution

$\frac{1}{\lambda}=\mathrm{RZ}^{2}\left[\frac{1}{\mathrm{n}_{1}^{2}}-\frac{1}{\mathrm{n}_{2}^{2}}\right]=\mathrm{R} \times 2^{2}\left[\frac{1}{\mathrm{l}^{2}}-\frac{1}{2^{2}}\right]$ $\Rightarrow 3 \mathrm{R} ; \lambda=\frac{1}{3 \mathrm{R}}$

Hence, the correct answer is option: 'C'.

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