Please help I have no idea how to do this.

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.)

To determine the structures of X, Y, and Z, we need to follow a systematic approach by analyzing the given information.

1. Start by drawing the Lewis structure for one of the three dichloroethylenes, let's start with X.

Based on the molecular formula C2H2Cl2, we know that there are 2 carbon atoms, 2 hydrogen atoms, and 2 chlorine atoms.

We can begin by placing the carbon atoms in the center and connecting them with a double bond. Next, attach the two chlorine atoms to each carbon atom, and finally, add the hydrogen atoms as shown below:

Cl Cl
| |
H-C=C-C-H

This structure represents compound X.

2. Next, we know that compound Z has a dipole moment. This suggests that there is an unequal sharing of electrons, resulting in a polar molecule. Compound Z also combines with hydrogen to give the same product as compound X.

Since compound X has no dipole moment but still forms the same product with hydrogen, we can conclude that the hydrogen must add to one of the double bonds. This means that compound Z must have a double bond between the carbon atoms as well.

To create a dipole moment, we need to arrange the atoms such that one chlorine atom is closer to the hydrogen than the other. This can be achieved by placing the chlorine atoms on the same side of the double bond, as shown below:

Cl H
| |
Cl-C=C-H

This structure represents compound Z.

3. Finally, we need to determine the structure of compound Y. To do this, we can consider the remaining dichloroethylene.

Since compounds X and Z have been assigned with a double bond between the carbon atoms, compound Y must have a triple bond between the carbon atoms to differentiate it from the other two compounds.

Based on the information given, we can construct the structure of compound Y as follows:

Cl Cl
| |
H-C≡C-H

This structure represents compound Y.

In summary, the Lewis structures for compounds X, Y, and Z are as follows:
X: Cl-CH=CH-Cl
Y: Cl-C≡C-Cl
Z: Cl-CH=CH-Cl

Note: The assignment of lone pairs, radical electrons, and atomic charges was not specified in the question, so they have not been included in the structures.