Dichloroethylene (C2H2Cl2) has three forms (isomers), each of which is

Dichloroethylene (C2H2Cl2) has three forms (isomers), each of which is a different substance.
(a) Draw Lewis structures of the three isomers, all of which have a carbon-carbon double bond.
(b) Which of these isomers has a zero dipole moment?
(c) How many isomeric forms can chloroethylene, C2H3Cl, have? Would they be expected to have dipole moments?