See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

## Geometrical Isomerism Analysis **Key Concept:** Geometrical isomerism occurs in alkenes when two different groups are attached to each carbon of the $C=C$ double bond, allowing cis-trans arrangements. **Requirements for geometrical isomerism:** - Double bond must exist - Each carbon of the double bond must have **two different groups** attached **Analyzing each option:** **(A)** $H-C=C-I$ with $H$ and $Br$ on the other carbons - Left carbon: $H, H$ (identical groups) ✗ - Cannot show geometrical isomerism **(B)** $H_3C-C=C-I$ with $H$ and $Br$ on the right carbon - Left carbon: $H_3C, H$ (different) ✓ - Right carbon: $I, Br$ (different) ✓ - **Can exist as cis and trans isomers** ✓ **(C)** $H_3C-C=C-Cl$ with $H_3C$ and $Br$ on the left carbon - Left carbon: $H_3C, H_3C$ (identical groups) ✗ - Cannot show geometrical isomerism **(D)** $H-C=C-Cl$ with $H_3C$ and $Cl$ on both carbons - Right carbon: $Cl, Cl$ (identical groups) ✗ - Cannot show geometrical isomerism **Answer: (B)** is correct because both carbons of the double bond have two *different* substituents, enabling cis-trans isomerism.