See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Solution: Identifying Non-Superimposable Mirror Images (Chirality) **Key Concept:** A molecule has non-superimposable mirror images (is chiral) if it contains a stereocenter with **four different groups** attached. ## Analysis of Each Option: **(1) Cl—C(H)(Me)(CH₃):** Four groups: Cl, H, Me, CH₃ — but **Me and CH₃ are identical**. Not chiral. ✗ **(2) D—C(H)(C₂H₅)(CH₂CH₃):** Four groups: D, H, C₂H₅, CH₂CH₃ — but **C₂H₅ and CH₂CH₃ are identical** (ethyl groups). Not chiral. ✗ **(3) Br—C(H)(D)(CH₃):** Four groups: **Br, H, D, CH₃** — all four are **different** - D (deuterium) is isotopically distinct from H - This carbon is a true stereocenter - Has R/S configuration (non-superimposable enantiomers exist) ✓ **(4) H—C(Et)(Cl)(CH₂CH₃):** Four groups: H, Et, Cl, CH₂CH₃ — but **Et and CH₂CH₃ are identical**. Not chiral. ✗ ## Answer: **Option (3)** has non-superimposable mirror images because the stereocenter bears four chemically distinct groups: Br, H, D, and CH₃.