See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Solution: Geometric Isomerism Analysis **Geometric isomerism** requires: 1. A double bond (C=C) or restricted rotation 2. Two *different* groups on each carbon of the double bond Let me evaluate each option: **(A) Me and Et on benzene** - Aromatic ring: no C=C double bond available for geometric isomerism - Only positional (ortho/meta/para) isomers exist ❌ **(B) Naphthalene with Cl and Et substituents** - All substituents on sp² carbons (aromatic system) - No C=C with restricted rotation between different groups ❌ **(C) Naphthalene with Br substituents** - Both Br atoms on the naphthalene ring - No C=C double bond with two different groups at each end ❌ **(D) Tri-aromatic system with mixed substituents** - Central benzene ring has two different groups: **Cl** (top) and **Br** (bottom) - The two flanking benzene rings are **not identical** (one has Me/Et, the other has Br/Me) - This creates a C=C-like restricted rotation between the central and flanking rings - Since both ends of this "double bond" have different substituents, **cis/trans (E/Z) isomers are possible** ✓ **Answer: (D)** — The asymmetrically substituted biaryl/triaryl system has restricted rotation between aromatic rings with different group arrangements on each side, enabling geometric (cis/trans) isomerism.