According to Bohr's theory of 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 Planck's constant.

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

Hence, angular momentum is quantized.

The energy of electron in $n$th orbit of hydrogen atom,

$E =$ $\frac{Rhc}{n^2}$ joule

Thus, it is obvious that the hydrogen atom has some characteristics 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 quantized.