See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Geometrical Isomerism Analysis **Geometrical (cis-trans) isomerism** requires: 1. A C=C double bond 2. **Two different groups on each carbon** of the double bond Let me evaluate each option: **(A) 2-butene:** $CH_3-CH=CH-CH_3$ - Structure: $CH_3$ and $H$ on one carbon; $CH_3$ and $H$ on the other - Shows **cis-trans isomerism** ✓ **(B) Propene:** $CH_2=CH-CH_3$ - Structure: Two $H$ atoms on C1; one $CH_3$ and one $H$ on C2 - **C1 has identical groups** ($H$ and $H$) → **No isomerism** ✗ **(C) 1-phenylpropene:** $C_6H_5-CH=CH-CH_3$ - Structure: $C_6H_5$ and $H$ on C1; $CH_3$ and $H$ on C2 - Shows **cis-trans isomerism** ✓ **(D) 2-methyl-2-butene:** $(CH_3)_2C=CH-CH_3$ - Structure: Two $CH_3$ groups on one carbon (identical) - **No isomerism** ✗ **Answer:** The question asks which **will NOT** show geometrical isomerism. **Propene (B)** lacks different substituents on one of the double-bonded carbons, making cis-trans isomerism impossible.