What is the excited state of an atom?

What is the energy of the electron revolving in the third orbit expressed in $ eV $ (in $eV$)?

If an electron in the excited state falls to the ground state,a photon of energy $5 \ eV$ is emitted. The wavelength of the photon is nearly: (in $nm$)

If $n$ is the orbit number of the electron in a hydrogen atom,the correct statement among the following is

$\frac{x}{x+4}$ is the ratio of energies of photons produced due to the transition of an electron of a hydrogen atom from its $(i)$ third permitted energy level to the second level and $(ii)$ the highest permitted energy level to the second permitted level. The value of $x$ will be.

The ratio of energies of photons produced due to the transition of an electron in a hydrogen atom from its $(a)$ second to first energy level and $(b)$ highest energy level to the second level is: