CBSE Class 11-science Answered

The shortest wavelength transition in the Paschen series in hydrogen occurs at 821 nm. According to the equation, the allowed energies of one electron atoms and ions are propotional to Z², so we can expect the frequencies of the transitions between the same two levels to scale as Z² too. Because wavelength is inversely propotional to the frequency. It follows that the wavelength of the transition should scale as 1/Z². Therefore, the same transition in Li²⁺ (For which Z=3) can be expected to lie at = 91.2 nm