Question

Bohr model ${}^{\prime }{H}^{\prime }$ atom, $e^{-}$ transferred from $5^{th}$ orbit to grd state. How many reversible spectral lines possible?

Answer 1

The number of spectral lines produced when a electron gets transition from $n^{th}$ state to ground state is $\Sigma (n-1)$

So if electron gets transition from fifth state to ground state then total spectral lines produced is $\Sigma (5-1)=4+3+2+1=10$