What is the point group of SO3?

Answer 1

C2v was written by a previous answerer. This would nearly be true if the double bound O stayed as a double bond, but that resonates throughout the 3 Os, therefore the symmetry is trigonal planar. So it has a c3 axis but also 3 c2's. therefore it is D3H.

Answer 2

The SO4 anion is tetrahedral, so its point group is Td.

Answer 3

The point group of SO3 (sulfur trioxide) is D3h. This point group has 6 symmetry operations including a three-fold rotation axis (C3), three perpendicular C2 rotation axes, and six mirror planes.