Chemistry - STEREO ISOMERISM Question with Solution | TestHub

CIP priorities : at the left carbon CH₃ $>$ H; at the right carbon C₂H₅ $>$ CH₃. In the correct structure the higher-priority groups CH₃ and C₂H₅ lie on the same side of the double bond, so it is the Z-isomer.

The first structure is 2-methyl-2-butene : two identical CH₃ groups on one double-bond carbon, so E/Z isomerism is not possible. The second structure has the higher groups (C₆H₅ and COOH) on opposite sides (E). The fourth is trans-cinnamic acid (E).