The total energy of an electron in the first excited state of the hydrogen atom is $-3.4 \ eV$. Find out its potential energy in this state.

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

$A$ hydrogen atom emits blue light when it changes from the $n = 4$ energy level to the $n = 2$ level. Which colour of light would the atom emit when it changes from the $n = 5$ level to the $n = 2$ level?

The total energy of an electron in the $n^{th}$ stationary orbit of the hydrogen atom can be obtained by

The diagram below 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 $(-12\,eV)$ by emitting exactly two photons. Which of the following energies could not belong to either of the photons (in $eV$)?

The first excited state of a hydrogen atom is $10.2 \ eV$ above the ground state. What temperature is needed to excite a hydrogen atom to its first excited state?