The minimum energy required to excite a hydrogen atom from its ground state is.....$ eV$.

The following diagram indicates the energy levels of a certain atom. When the system moves from the $2E$ level to the $E$ level,a photon of wavelength $\lambda$ is emitted. The wavelength of the photon produced during its transition from the $\frac{4E}{3}$ level to the $E$ level is

Due to transitions among its first three energy levels,a hydrogenic atom emits radiation at three discrete wavelengths $\lambda_1, \lambda_2$ and $\lambda_3$ (where $\lambda_1 < \lambda_2 < \lambda_3$). Then,

The energy of an electron in the $n^{th}$ orbit of a hydrogen atom is given by $E_n = - \frac{13.6}{n^2} \ eV$. How much energy in $eV$ is required to move an electron from the first orbit to the third orbit?

The binding energy of a hydrogen atom in the ground state is $13.6 \ eV$. The energies required to remove an electron from the first three energy levels of the hydrogen atom are,respectively,(in $eV$):

The following diagram indicates the energy levels of a certain atom. When the system moves from the $4E$ level to the $E$ level,a photon of wavelength ${\lambda _1}$ is emitted. The wavelength of the photon produced during its transition from the $\frac{7}{3}E$ level to the $E$ level is ${\lambda _2}$. The ratio $\frac{{{\lambda _1}}}{{{\lambda _2}}}$ will be: