Question

If the shortest wave length of Lyman series of H atom is x, then the wave length of the first line of Balmer series of H atom will be –

• A. 9x/5
• B. 36x/5
• C. 5x/9
• D. 5x/36

Answer 1

Answer: (B)

36x/5

Answer 2

Shortest wave length of Lyman series of H-atom

$\frac{1}{\lambda} = \frac{1}{x}R = \left\lbrack \frac{1}{(1)^{2}} - \frac{1}{(\infty)^{2}} \right\rbrack so, x = \frac{1}{2}$

For Balmes series

$\frac{1}{\lambda} = R(1)^{2}\left\{ \frac{1}{(2)^{2}} - \frac{1}{(3)^{2}} \right\}$

$\frac{1}{\lambda} = \frac{1}{x} \times \frac{5}{36} so, \lambda = \frac{36}{5}$.s