The number of spectral lines emitted by atomic hydrogen that is in the $4^{\text{th}}$ energy level is

If energy of $15 \ eV$ is given to an electron in the $4^{th}$ orbit,find its final energy when it comes out of the $H$-atom. (in $eV$)

The diagram shows different transitions across the energy levels for an electron in a certain atom. Among these,which transition represents the emission of a photon with the most energy?

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

An electron makes a transition from an excited state to the ground state of a hydrogen-like atom. Out of the following statements, which one is correct?

The ground state energy of a hydrogen atom is $-13.6 \ eV$. The potential energy of the electron in the first excited state of hydrogen is (in $eV$)