Please help I have no idea how to do this.

Question

There are three different dichloroethylenes (molecular formulaC2H2Cl2), which we can designate X, Y, and Z.
Compound X has no dipole moment, but compound Z does.
Compounds X and Z each combine with hydrogen to give the same product:

C2H2Cl2 (X or Z) + H2 → ClCH2single bondCH2Cl.

What are the structures of X, Y, and Z? (Draw complete Lewis structures. Assign lone pairs, radical electrons, and atomic charges where appropriate.)