No, AlCl3 does not contain a C3 axis and a horizontal plane. When we draw the Lewis structure for AlCl3, it forms a trigonal planar shape with the aluminum atom at the center and three chlorine atoms arranged symmetrically around it. This arrangement only has a C3 rotational symmetry, meaning it can be rotated 120 degrees around an axis passing through the aluminum atom and perpendicular to the plane. There is no horizontal plane of symmetry in this molecule.
