How many stereocenter containing isomers of c5h10 are there where the molecule must contain one ring? I identified the cis and trans forms of 1,2-dimethylcyclopropane, but I think my TA said there was one more form containing a cyclopropane ring.... but I can't remember for sure. Is C1 on 1,1-dimethylcyclopropane a stereocenter? It doesn't seem to have four different substituents. So confusing.