Benzil has two electronegative oxygens that can produce a dipole moment while benzophenone only has one, but does benzil have cis/trans isomers?
From the images of the structure of benzil, if the ketone groups are facing opposite directions, you get a net 0 diploe moment because they cancel. But if you have a cis molecule, then they both face the same direction. So would it make more sense that cis-benzil is more polar than benzophenone while trans-benzil is less polar than benzophenone?