Question

The wave number of the limiting line in Lyman series of hydrogen is 109678 cm^–1. The wave number of the limiting line in Balmer series of He⁺ would be –

• A. 54839 cm^–1
• B. 219356 cm^–1
• C. 109678 cm^–1
• D. 438712 cm^–1

Answer 1

Answer: (C)

109678 cm^–1

Answer 2

R_H = 109678 cm^–1

Wave number of the limiting line in Balmer Series of He⁺

= R_H. Z² $\left( \frac{1}{{n_{1}}^{2}}–\frac{1}{{n_{2}}^{2}} \right)$

= 109678 × (2)² $\left\lbrack \frac{1}{(2)^{2}}–\frac{1}{\infty} \right\rbrack$

= 109678 cm^–1