How much energy is needed to release the electron from the second excited state in the hydrogen atom (in $eV$)?

$A$ hydrogen atom at the ground level absorbs a photon and is excited to $n=4$ level. The potential energy of the electron in the excited state is

The energy of an electron in the fourth excited state of the hydrogen atom is

The total energy of a hydrogen atom in its ground state is $-13.6 \ eV$. If the potential energy in the first excited state is taken as zero,then the total energy in the ground state will be ..... $eV$.

The ground state energy of the hydrogen atom is $-13.6 \ eV$. The kinetic and potential energy of the electron in the second excited state are,respectively:

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: