The angular momentum of an electron in the $7^{th}$ Bohr orbit of a hydrogen atom is given by:

The ground state energy of $H$ is equal to

Electrons with a kinetic energy of $6.023 \times 10^4 \ J/mol$ are evolved from the surface of a metal when it is exposed to radiation of wavelength $600 \ nm$. The minimum amount of energy required to remove an electron from the metal atom is

Calculate the ratio of the radius of the $2^{nd}$ and $3^{rd}$ orbit of a hydrogen atom. (Note: $r_n \propto n^2$)

Number of waves made by Bohr's electron in one complete revolution in the $3^{rd}$ orbit.

Which are the drawbacks of Rutherford's atomic model?