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

The energy levels of an electron in an atom are shown. Which transition of the electron represents the emission of a photon with the highest energy?

In a hydrogen atom,which of the following electronic transitions would involve the maximum energy change?

$\frac{x}{x+4}$ 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.

Energy of $H$-atom in the ground state is $-13.6 \; eV$. The energy needed to ionize a hydrogen atom which is in its second excited state is ....... $eV$.

If $13.6 \ eV$ energy is required to ionize the hydrogen atom,then the energy required to remove an electron from $n=2$ is (in $eV$)