Ionisation energy for H⁺ ion is proportional to rⁿ, then value of n is

Rutherford model could not explain

Ionisation energy of H-atom is 13.6 eV. The wavelengths of the spectral line emitted when an electron in Be³⁺ comes them 5th energy level to 2nd energy level is

If the quantum number I could have the value 'n' also then, Sc(21) would have electronic configuration as (other rules strictly followed)