Question

Ratio of the wavelengths of first line of Lyman series and first line of Balmer series is

• A. 1 : 3
• B. 27 : 5
• C. 5 : 27
• D. 4 : 9

Answer 1

Answer: (C)

5 : 27

Answer 2

For Lyman series $\frac{1}{\lambda_{L_{1}}} = R\left\lbrack \frac{1}{1^{2}} - \frac{1}{2^{2}} \right\rbrack = \frac{3R}{4}$ …..(i)

For Balmer series $\frac{1}{\lambda_{B_{1}}} = R\left\lbrack \frac{1}{2^{2}} - \frac{1}{3^{2}} \right\rbrack = \frac{5R}{36}$ …..(ii)

From equation (i) and (ii) $\frac{\lambda_{L_{1}}}{\lambda_{B_{1}}} = \frac{5}{27}$.