Final answer:
Geometric isomers have the same connectivity but different arrangements of atoms in space. For each compound mentioned, draw a stereoisomer by changing the arrangement of the specified groups. Cis-1,2-dimethylcyclobutane does not have enantiomers due to its plane of symmetry.
Step-by-step explanation:
Geometric isomers, also known as cis-trans isomers, have the same connectivity but differ in the arrangement of their atoms in space. To draw the structure of a compound that is a stereoisomer of trans-1,2-dimethylcyclobutane, we need to change the arrangement of the methyl groups. For example, we can draw a cis-1,2-dimethylcyclobutane by placing both methyl groups on the same side of the cyclobutane ring.
Similarly, to draw the structure of a stereoisomer of cis-1,4-dibromocyclohexane, we need to change the arrangement of the bromine atoms. For instance, we can draw a trans-1,4-dibromocyclohexane by placing the bromine atoms on opposite sides of the cyclohexane ring.
Lastly, cis-1,2-dimethylcyclobutane itself is a stereoisomer. It does not have enantiomers because it has a plane of symmetry. To draw a different stereoisomer, we can switch the arrangement of the methyl groups.