Question

An electron in the hydrogen atom is de-excited from $5^{th}$ orbit to $1^{st}$ orbit. The number of spectral lines the element is expected to emit:

• A. 5
• B. 4
• C. 10
• D. 12

Answer 1

The correct option is C 10

The general formula for calculating number of spectral lines
= $\frac{(n_H-n_L)(n_H-n_L+1)}{2}$
$n_H=5$, $n_L=1$
$\text{Number of spectral lines}=\frac{(5-1)(5-1+1)}{2}$
$=\frac{\left(4\right)\left(5\right)}{2}$
$=10$