Question

If $x.R$ is the wave number of third emission line in the atomic spectrum of hydrogen in the Balmer Series then the value of $x$ will be:

($R=$ Rydberg constant).

• A. $0.21$
• B. $20$
• C. $\frac{1}{9}$
• D. $\frac{10}{21}$

Answer 1

The correct option is A $0.21$

For Balmer series:

$n_{initial}=2$.

For third emission, $n_{final}=5$.

$\overline{\upsilon }=109677[\frac{1}{n_1^2}-\frac{1}{n_2^2}]$

$\overline{\upsilon }=109677[\frac{1}{4}-\frac{1}{25}]$

$\overline{\upsilon }=R\left[\frac{21}{100}\right]$

$\overline{\upsilon }=0.21R$