See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Geometric Isomerism Analysis **Geometric isomerism** requires: 1. A C=C double bond (restricted rotation) 2. Two different groups on each carbon of the double bond ## Evaluating each option: **(1) & (2):** Both have $CH_2$ as the exocyclic group - The two carbons of the double bond are: $CH_2$ and $C$ (from cyclohexene ring) - Each carbon has identical groups on the other side (both bonded to the ring carbons) - **No geometric isomerism** — only one structure possible **(3) & (4):** Both have $CHCl$ as the exocyclic group - The two carbons of the double bond are: $CHCl$ and $C$ (from ring) - The $CHCl$ carbon has **two different groups**: $H$ and $Cl$ - The other double bond carbon has **two different ring substituents**: one with a methyl group (in structure 3 or 4) and one without - **Geometric isomerism exists**: $cis$ and $trans$ configurations are possible Comparing structures (3) and (4): - **(3)** has the methyl group and double bond in specific spatial arrangement - **(4)** has the methyl group and double bond in the opposite spatial arrangement - These represent **cis-trans isomers** **Answer: Option (4)** is the geometric isomer of option (3) because both molecules have restricted rotation about the $C=CHCl$ double bond with different groups on each carbon, and they differ in the spatial orientation of substituents (trans relationship in one vs cis in the other).