Chemistry - Atomic Structure Question with Solution | TestHub

${\mathbf{X}}^{\mathbf{a}+}$ and ${\mathbf{Y}}^{\mathbf{b}+}$ are hydrogen-like species. The wavelength of light absorbed during the transition between the states with principal quantum numbers $\mathrm{n}=1$ and $\mathrm{n}=2$ of ${\mathbf{X}}^{\mathbf{a}+}$ is 1. The wavelength of light absorbed during the transition between the states with principal quantum numbers $\mathrm{n}=2$ and $\mathrm{n}=4$ of ${\mathbf{Y}}^{\mathbf{b}+}$ is 91. The lowest possible value of $(\mathbf{a}+\mathbf{b})$ is $\_\_\_\_$.