The ratio of the shortest wavelength of Balmer series to the shortest wavelength of Lyman series for hydrogen atom is :

The angular momentum of an electron in a hydrogen atom is proportional to : (Where $$\mathrm{r}$$ is the radius of orbit of electron)

An electron rotates in a circle around a nucleus having positive charge $$\mathrm{Ze}$$. Correct relation between total energy (E) of electron to its potential energy (U) is :

According to Bohr's theory, the moment of momentum of an electron revolving in $$4^{\text {th }}$$ orbit of hydrogen atom is: