Physics - Modern Physics Question with Solution | TestHub

An excited ${\left(He\right)}^{+}$ ion emits two photons in succession, with wavelengths $108.5nm$ and $30.4nm$ in making a transition to the ground state. The quantum number $n$, corresponding to its initial excited state is

(for a photon of wavelength $\lambda$, energy $E=\frac{1240eV}{\lambda (innm)}$)