An electron of a hydrogen atom in an excited state has an energy $E_n = -0.85 \ eV$. The maximum number of allowed transitions to lower energy levels is:

Out of the following transitions in a hydrogen atom,identify the transition which emits photons of highest frequency.

The energy of the highest energy photon of the Balmer series of the hydrogen spectrum is close to $... eV$.

The energy of a hydrogen atom in its ground state is $-13.6 \,eV$. The energy of the level corresponding to $n=7$ is ...... $eV$.

The diagram shows the lowest four energy levels for an electron in a hypothetical atom. The electron is excited to the $-1\, eV$ level and transitions to the lowest energy state by emitting exactly two photons. Which of the following energies could not belong to either of the photons (in $, eV$)?

$A$ free electron of $2.6 \, eV$ energy collides with a $H^+$ ion. This results in the formation of a hydrogen atom in the first excited state and a photon is released. Find the frequency of the emitted photon. $(h = 6.6 \times 10^{-34} \, J \cdot s)$