Chemistry - STEREO ISOMERISM Question with Solution | TestHub

cis-1-Chloro-3-methylcyclobutane has a plane of symmetry passing through C₁ and C₃ (and their substituents Cl and CH₃), bisecting the ring - the two halves of the ring are mirror images, so the cis isomer is achiral. In trans-1-chloro-3-methylcyclobutane (Cl down, CH₃ up) no such plane exists, so the trans isomer is chiral and exists as a pair of enantiomers.