The spectrum of a hydrogen - like ion in the Third Balmer line has a wavelength of 108.5 nm. Then number of protons in the nucleus of the ion is
4
5
3
2
(4)
For the Third Balmer line,
hcλ=ΔE=13.6 × Z2 × 122 −152 ∴ 124201085=13.6 × Z2 × 21100 ⇒ Z=2