What is the total energy of an electron at an infinite distance from the nucleus in an atom?

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:

Find the ratio of energies of photons produced due to the transition of an electron in a hydrogen atom from its $(i)$ second permitted energy level to the first level,and $(ii)$ the highest permitted energy level to the first permitted level.

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

The ionization potential of a hydrogen atom is $13.6 \text{ eV}$. How much energy needs to be supplied to ionize a hydrogen atom in the first excited state (in $\text{ eV}$)?

The figure shows the energy levels $P, Q, R, S$ and $G$ of an atom,where $G$ is the ground state. $A$ red line in the emission spectrum of the atom is obtained by an energy level transition from $Q$ to $S$. $A$ blue line can be obtained by which of the following energy level transitions?