As the quantum number $n$ increases,the difference in energy between consecutive energy levels

If the electron in a hydrogen atom moves from the ground state orbit to the $5^{\text{th}}$ orbit,then the potential energy of the electron

Consider the following electronic energy level diagram of $H-$ atom. Photons associated with shortest and longest wavelengths would be emitted from the atom by the transitions labelled:

$A$ hydrogen atom (ionisation potential $13.6 \ eV$) makes a transition from the third excited state to the first excited state. The energy of the photon emitted in the process is.......$eV$.

$A$ hydrogen atom makes a transition from $n = 2$ to $n = 1$ and emits a photon. This photon strikes a doubly ionized lithium atom $(Z = 3)$ in an excited state and completely removes the orbiting electron. The least quantum number for the excited state of the ion for this process is:

When a hydrogen atom emits a photon during a transition from $n=4$ to $n=2$,its recoil speed is about (in $m \ s^{-1}$)