Question

In which transition of hydrogen atom is the wavelength of 486.1 nm produced? To which series does it belong? 

Answer 1

The wavelength λ = 486.1 nm corresponds to the transition energy of E = 1241/486.1 = 2.55 eV 

Looking up Fig. 2.1, for the energy level diagram for hydrogen atom, the transition n = 4 → 2 gives the energy difference −0.85 − (−3.4) = 2.55 eV 

The line belongs to the Balmer series.