If the ionization energy of a hydrogen atom in the ground state is $13.6 \ eV$,find the ionization potential of the third orbit in $eV$.

If the electron in a hydrogen atom were in the energy level with $n = 3$,how much energy in joule would be required to ionise the atom? (Ionisation energy of $H$-atom is $2.18 \times 10^{-18} \ J$):

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

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

The ratio of energies of photons produced due to transition of an electron in a hydrogen atom from the second energy level to the first energy level and from the fifth energy level to the second energy level is:

In an atom,an electron requires $47.2 \, eV$ of energy to transition from the $n = 2$ orbit to the $n = 3$ orbit. The atomic number $Z$ of the atom is: