$A$ photon is emitted in transition from $n = 4$ to $n = 1$ level in a hydrogen atom. The corresponding wavelength for this transition is $......... \, nm$ (given,$h = 4 \times 10^{-15} \, eV \cdot s$ and $c = 3 \times 10^8 \, m/s$):

An electron of a hydrogen-like atom,having $Z=4$,jumps from the $4^{\text{th}}$ energy state to the $2^{\text{nd}}$ energy state. The energy released in this process will be $......... \text{eV}$.
(Given $Rch = 13.6 \text{ eV}$)
Where $R =$ Rydberg constant,
$c =$ Speed of light in vacuum,
$h =$ Planck's constant.

Explain emission lines and absorption lines.

The ratio of energies of photons produced due to the transition of an electron of a hydrogen atom from its $(i)$ second to first energy level and $(ii)$ highest energy level to $2^{nd}$ level is respectively: (in $: 1$)

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?

Total energy of an electron in an excited state of a hydrogen atom is $-3.4 \text{ eV}$. Find the kinetic and potential energy of the electron in this state.