Question

No. of visible lines when an electron returns from $5th$ orbit to ground state in $H$ spectrum are:

• A. $5$
• B. $4$
• C. $3$
• D. $10$

Answer 1

The correct option is D $10$

Number of visible lines when an electron returns from 5th orbit to the ground state in the H spectrum is 10.
The number of spectral lines $=\frac{n(n-1)}{2}$.

The number of spectral lines $=\frac{5(5-1)}{2}=10$.

These lines belong to the UV region.
Note: Lyman series corresponds to transitions to $n=1$ level.

So, the correct option is $D$