Not considering the electronic spin, the degeneracy of the second excited state `(n = 3)` of H-atom is 9, while the degeneracy of the second excited state of `H^(-)` is

Answer

3

Explanation

Auf-bau rule is not obeyed by single electronic species. So, for H atom, order of energy is
`1s lt 2s= 2p lt 3s = 3p = 3d lt ...`
The degenerancy is `1+3 +5 = 9`
`( :' 3s +3p +3d)` and for `H^(-)` ions, `1s lt 2s lt 2p lt 3s lt`... The degenerancy is `3 ( :' 2p)`