Question

The longest wavelength present in the Balmer series of hydrogen, corresponding to H_a line is –

• A. 656 nm
• B. 565 nm
• C. 400 nm
• D. 700 nm

Answer 1

Answer: (A)

656 nm

Answer 2

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

n_f = 2 ; n_i = 3

R = 1.097 × 10⁷/m

\lambda = 656nm \end{matrix}$$