Hydrogen  (1H1), Deuterium (1H2) ,singly ionized Helium (2He4)+  and doubly ionized   (3Li6)++  all have one electron around the nucleus. Consider an electron transition from  n=2 to n=1.If the wavelengths of emitted radiation are λ1,λ2,λ3     and λ4  respectively then approximately which one of the following is correct?