text: Determining the point group is a useful way to predict polarity of a molecule. In general, a molecule will not possess dipole moment if the individual bond dipole moments of the molecule cancel each other out. This is because dipole moments are euclidean vector quantities with magnitude and direction, and a two equal vectors that oppose each other will cancel out.
  Any molecule with a centre of inversion ("i") or a horizontal mirror plane ("σ") will not possess dipole moments. 
  Likewise, a molecule with more than one C axis of rotation will not possess a dipole moment because dipole moments cannot lie in more than one dimension. As a consequence of that constraint, all molecules with dihedral symmetry (D)  will not have a dipole moment because, by definition, D point groups have two or multiple C axes.
  Since C, C,C C and C point groups do not have a centre of inversion, horizontal mirror planes or multiple C axis, molecules in one of those point groups will have dipole moment.