See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Geometric Isomerism Analysis **Geometric isomerism** occurs when groups are rigidly fixed in space and cannot rotate freely (double bond or ring constraint). ## Option (A): Dichloroethene ($CH_2=CCl_2$) - Has a $C=C$ double bond with **two different groups on one carbon** (two $Cl$ atoms) - Cannot form cis-trans isomers because the two chlorines are identical - ❌ No geometric isomerism ## Option (B): $CH_3-CH=N-OH$ - Has a $C=N$ double bond with **different groups on each atom** - Carbon: $CH_3$ and $H$ (different) - Nitrogen: $OH$ and $H$ (different) - The $C=N$ bond is rigid and prevents rotation - Forms **cis-trans isomers**: $CH_3$ and $OH$ can be on same side (cis) or opposite sides (trans) - ✅ **Shows geometric isomerism** ## Option (C): Cyclooctene - Contains a $C=C$ double bond within a ring - Different groups on each carbon of the double bond - The ring's rigidity prevents free rotation about the double bond - Forms **cis-trans isomers** based on ring attachment positions - ✅ **Shows geometric isomerism** ## Conclusion Options **(B)** and **(C)** both exhibit geometric isomerism, making **(D) "all of the above"** the correct answer.