If an electron falls from $n = 3$ to $n = 2$,then the emitted energy is $..........$ $eV$.

Find the frequency of light that corresponds to photons of energy $5.0 \times 10^{-5} \ erg$.

When $\beta$-particles are sent through a tin metal foil,most of them go straight through the foil as

The energy of the second Bohr orbit of the hydrogen atom is $-3.4 \ eV$. The energy of the fourth Bohr orbit of the $He^{+}$ ion will be: (in $eV$)

In which hydrogen-like ion is the difference in wavelength between the first line of the Balmer series and the first line of the Lyman series equal to $59.3 \ nm$? $[R_H = 109678 \ cm^{-1}]$

Which of the following relations is correct for the energy of the ground state of hydrogen-like species?