Question

The electron present in the $5$th orbit in an excited hydrogen atom returns back to the ground state. The number of lines which appear in Lyman series of hydrogen spectrum is:

• A. $5$
• B. $10$
• C. $4$
• D. $6$

Answer 1

The correct option is C $4$

The number of lines which appear in Lyman series can be calculated by the following formula:

Number of spectral lines in a series $=n_2-n_1$, where $n_2$ and $n_1$ are excited state and ground state respectively.

Number of spectral lines in Lyman series $=n_2-n_1=5-1=4$

Hence, $4$ lines appear in Lyman series of hydrogen spectrum when an electron present in $5^{th}$ orbit in an excited hydrogen atom returns back to the ground state.