For the ground state, the electron in the H-atom has an angular momentum =ħ according to the simple Bohr model. Angular momentum is a vector and hence there will be infinitely many orbits with the vector pointing in all possible directions. In actuality, this is not true,

Question

Philoid · Accepted Answer

According to Bohr model, angular momentum (L=mvr_n) of revolving electron must be integral multiple of

(where h is plank constant) i.e. mvr_n

this actually only gives the magnitude of angular momentum and direction can’t be concluded. That’s why it is wrong to say that H-atom has an angular momentum =ħ. So Bohr model doesn’t provide correct value of angular momentum.

Therefore option (a) is correct.