For the ground state, the electron in the H-atom has an angular momentum = $\frac{\mathrm{h}}{2\mathrm{\pi }}$, 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,

1. because Bohr model gives incorrect values of angular momentum

2. because only one of these would have a minimum energy

3. angular momentum must be in the direction of spin of the electron

4. because electrons go around only in horizontal orbits

(1) Hint: The Bohr model does not give the direction of angular momentum.
In the simple Bohr model, only the magnitude of angular momentum is kept equal to some integral multiple of $\frac{h}{2\mathrm{\pi }}$, where, h is Planck's constant and thus, the Bohr model gives incorrect values of angular momentum.