How many isomers does ${{C}_{2}}{{H}_{4}}C{{l}_{2}}$ have?

Hint Isomers are defined as the molecules which have the same molecular formula but different molecular geometries. There are two types of isomers such as conformational isomers and constitutional isomers.

Complete step by step solution:
Given in the question,
The formula of compound =${{C}_{2}}{{H}_{4}}C{{l}_{2}}$
Now we know that the alkene having 2 carbon atoms have the general formula ${{C}_{2}}{{H}_{6}}$ , in the given compound the two hydrogens are replaced with two chlorine groups.
There are two structural isomers possible for the given compound. The second chlorine atom can be placed on the same carbon, where the first chlorine atom is present. Or the second chlorine atom can be placed on the second carbon. The two isomers are 1,2-dichloroethane and 1,1-dichoroethane.

Additional information:
We know that there is no superimposable mirror image and there is no plane of symmetry in the molecule then the molecule is known as chiral. And the chiral carbon has four different groups attached to the carbon. This property is known as chirality and the compounds which have the same molecular formula but different compounds are said to be isomers. The compounds which are mirror images but are not identical to each other. They are known as enantiomers.

Note: Structural isomers are defined as compounds which have the same molecular formula but different connectivity of atoms or bonds. The isomers which are different by the orientation of atoms in space are known as stereoisomers and the isomers which differ by their rotation around a single bond are known as conformational isomers.