In a container a mixture is prepared by mixing of three samples of hydrogen helium ion `(He^(+))` and lithium ion `(Li^(2+)).` In sample , all the hydrogen atoms are in 1st excited state and all the `He^(+)` ions are in third excited state and all the `Li^(2+))` ions are in fifth excited state. Find the total number of spectral lines observed in the emission spectrum of such a sample when the electrons return back to the ground state.

Answer

`20`

Explanation

But `(H_(2))_(2 to 1)=(He^(+))_(4 to 2)=(Li^(2+))_(6 to 3)` are lines same energy and so, will overlap each other.
`:.` Total no. of lines observed `=(1+6+15)-2=20` lines.