See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Analysis of Optical Activity **Optical activity requires a chiral center** (stereocenter with four different groups attached). ## Compound (A): Diethyl sulfoxide $$\text{CH}_3-\text{S}(=\text{O})-\text{C}_2\text{H}_5$$ - Sulfur has **four different groups**: $CH_3$, $C_2H_5$, oxygen, and a lone pair - Sulfur is a stereocenter → **Optically active** ✓ ## Compound (B): Parallelogram shape - This is a **planar, symmetric achiral structure** (likely a cyclic alkene) - No chiral centers → Should **NOT be optically active** ✗ - *However, if this represents a specific chiral polycyclic structure, it could be active* ## Compound (C): Substituted biphenyl $$\text{Br}, \text{CH}_3, \text{Cl, NO}_2\text{CH}_3 \text{ on aromatic rings}$$ - The two benzene rings are **twisted out of planarity** due to steric hindrance - This creates **axial chirality** (chiral axis between the two rings) - Four different substituents prevent free rotation → **Optically active** ✓ ## Compound (D): Conjugated diene system $$\text{H}_3\text{C-(diamond chain)-CH}_3$$ - The diamond structure suggests **conjugated double bonds with symmetric end groups** ($CH_3$ and $CH_3$) - This molecule is **achiral and symmetric** → **NOT optically active** ✗ **Answer: A and C are optically active** (B is likely included as an exception based on specific stereochemistry)