# Rotation occurs freely around what hybridization?

All hybrid orbitals can only make $\sigma$ bonds (i.e. a single bond, or the first bond in a double or triple bond). These $\sigma$ bonds are formed from atomic orbitals that are infinitely symmetric about the internuclear axis. That means a rotation about the internuclear axis by an infinitely small angle returns the same molecule back.
Therefore, any $\sigma$ bond can rotate without breaking the symmetry of the molecule (the symmetry must be maintained in order for the bond to stay intact).