Hydrogen (1H1), deuterium (1H2), singly ionised helium (2He4)+ and doubly ionised lithium (3Li8)++ all have one electron around the nucleus. Consider an electron transition form n = 2 to n =1. If the wavelengths of emitted radiation are λ1, λ2, λ3 and λ4 a respectively for four elements, then approximately which one of the following is correct?
(a) 4λ1 = 2λ2 = 2λ3 = λ4
(b) λ1 = 2λ2 = 2λ3 = λ4
(c) λ1 = λ2 = 4λ3 = 9λ4
(d) λ1 = λ2 = 3λ3 = 4λ4
