1,3-cyclopentanediol has 3 possible stereoisomers. Two of which are enantiomers and are therefore, optically active, while one is optically inactive. The enantiomers are the trans- isomers which are (1R,3R)-1,3-Cyclopentanediol, and (1S,3S)-1,3- Cyclopentanediol.
The stereoisomer that is not optically active is the cis- isomer which is (1S,3R)-1,3-Cyclopentanediol and is shown in the illustration below.
