See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Solution: Identifying Geometrical Isomers **Step 1: Analyze Structure (i)** $$\text{Cl-C=C-Br (with H and Br on opposite sides)}$$ - Molecular formula: $C_2HClBr_2$ - Has two different groups on each carbon of the double bond **Step 2: Analyze Structure (ii)** $$\text{H-C=C-CH_3 (with Cl and Br)}$$ - Molecular formula: $C_3H_3ClBr$ - One carbon has two different substituents (H and Cl) - Other carbon has one H and one $CH_3$ (but $CH_3$ makes it different) - **Different molecular formula from (i)** — NOT isomers with (i) **Step 3: Analyze Structure (iii)** $$\text{Cl-C=C-H (with Br and H)}$$ - Molecular formula: $C_2H_2ClBr$ - One carbon has Cl and Br; other has two H atoms - **Different molecular formula from (i)** — NOT isomers **Step 4: Analyze Structure (iv)** $$\text{H-C=C-CH_3 (with Cl and Br)}$$ - Molecular formula: $C_3H_3ClBr$ - **Same molecular formula as (ii)** - Both have $Cl$ and $Br$ on *the same carbon* of the double bond - Structures (ii) and (iv) are **cis-trans isomers** (different spatial arrangements with restricted rotation around $C=C$) **Conclusion:** Structures (ii) and (iv) form a geometrical isomer pair. **Answer: (3) ii and iv** ✓