Question

the minimum angular momentum of electron in hydrogen atom will be

Answer 1

Any spherically symmetric state of the electron corresponds to deterministically 0 total angular momentum and 0 angular momentum along any one direction. Spherically symmetric states correspond to the s orbitals (1s, 2s, 3s etc.)

Since angular momentum operators corresponding to any two non-parallel direction don't commute, the angular momentum can only be deterministically specified along one direction.

Answer 2

Hope it will help you.