The ionization energy of sodium in $kJ \ mol^{-1}$,if electromagnetic radiation of wavelength $242 \ nm$ is just sufficient to ionize a sodium atom,is . . . . . . .

The photoelectric effect occurs only when the incident light has more than a certain minimum:

The Bohr orbit radius for the hydrogen atom $(n = 1)$ is approximately $0.530 \ \mathring{A}$. The radius for the first excited state $(n = 2)$ orbit is ........... $\mathring{A}$

For any given series of spectral lines of atomic hydrogen,let $\Delta \bar{\nu} = \Delta \bar{\nu}_{\max} - \Delta \bar{\nu}_{\min}$ be the difference in maximum and minimum wavenumbers in $cm^{-1}$. The ratio $\Delta \bar{\nu}_{\text{Lyman}} / \Delta \bar{\nu}_{\text{Balmer}}$ is

The energy of an electron in the second Bohr orbit of a hydrogen atom is:

The ionization energy of an electron in an excited state of a hydrogen atom is $+0.85 \, eV$. What will be the energy of the emitted photon in $eV$ when it returns to the ground state?