Which have zero dipole moment :-1, 1-Dichloroethene     Cis-1, 2-dichloroethene Trans-1, 2-dichloroetheneNone of these

To determine which compound has zero dipole moment, we need to consider the molecular geometry and the polarity of the bonds.

1,1-Dichloroethene: This compound has two chlorine atoms bonded to the same carbon atom. The molecule is linear, and the chlorine atoms have equal electronegativity. Therefore, the bond dipoles cancel each other out, resulting in a molecule with zero dipole moment.

Cis-1,2-dichloroethene: In this compound, the two chlorine atoms are on the same side of the double bond. The molecule has a bent shape, and the chlorine atoms have different electronegativities. As a result, the bond dipoles do not cancel each other out, and the molecule has a nonzero dipole moment.

Trans-1,2-dichloroethene: In this compound, the two chlorine atoms are on opposite sides of the double bond. The molecule has a linear shape, and the chlorine atoms have equal electronegativities. Similar to 1,1-dichloroethene, the bond dipoles cancel each other out, resulting in a molecule with zero dipole moment.

Therefore, the compounds with zero dipole moment are 1,1-dichloroethene and trans-1,2-dichloroethene.