An electron revolves in an orbit around a stationary nucleus with atomic number $Z = 5$. The energy required to excite the electron from the $3^{rd}$ orbit to the $4^{th}$ orbit is .......... $eV$.

If the velocity of an electron in the $n^{th}$ orbit of a hydrogen atom is $0.0109 \times 10^{10} \, cm \, s^{-1}$,what is the value of $n$?

For hydrogen-like species,which of the following graphs provides the most appropriate representation of $E$ vs $Z$ plot for a constant $n$?
[$E$: Energy of the stationary state,$Z$: atomic number,$n$: principal quantum number]

The total energy of the electron of $H$ atom in the second quantum state is $-E_2$. The total energy of the $He^{+}$ ion in the third quantum state is

Calculate the energy of $1 \ mol$ of photons having a frequency of $4.0 \times 10^{14} \ Hz$.

How much energy is required to ionize a $H$ atom if the electron occupies the $n=5$ orbit? Compare your answer with the ionization enthalpy of the $H$ atom (energy required to remove the electron from the $n=1$ orbit).