Explanation: Constitutional isomers are the isomers having same molecular formula but have different connectivity of groups.
The two cyclic constitutional isomers of trans-1,2-dimethylcyclobutane having same ring size are:
- trans-1,1-dimethylcyclobutane
- trans-1,3-dimethylcyclobutane
These two isomers are shown in the image attached below.
