According to Bohr's theory of the $\mathrm{H}$ atom, electrons can revolve only in those orbits in which their angular momentum is an integral multiple of$\frac{h}{2\pi }$, where $h$ is Plank's constant.

Angular momentum = $mvr$=$\frac{2h}{2\pi }$

Hence, angular momentum is quantized.

The energy of an electron in $n^{th}$ orbit of the hydrogen atom,

$E =$ $\frac{Rhc}{n^2}$ $\mathrm{J}$

Thus, it is obvious that the hydrogen atom has some characteristics of energy state. In fact, this is true for the atom of each element, $ie,$ each atom has its energy quantized.
Hence, both energy and angular momentum are quantised.