Q. Number of spectral lines in Balmer series when an electron return from $7^{\text {th }}$ orbit to $1^{\text {st }}$ orbit of hydrogen atom are
Structure of Atom
Solution:
As only visible lines have to be calculated i.e. Balmer lines
$\therefore $ Visible lines when ground state $=2$
$n_{1}=2$
$\therefore $ Possible arrangements $7 \rightarrow 2,6 \rightarrow 2,5 \rightarrow 2,4 \rightarrow 2,3 \rightarrow 2$
Total number of spectral lines $=5$
All have visible region because $n_{1}=2$
