See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Solution: Identifying Superimposable Structures **Key Concept:** Two structures are superimposable if one can be rotated/reoriented in 3D space to perfectly overlap with the other (they are identical or enantiomers that don't match). ## Analysis of Each Structure **Structure (1):** - Central carbon with: Br, H, Me, HO, Et - Stereochemistry: Assign priorities using CIP rules - Br(1) > HO(2) > Et(3) > Me(4) - Configuration: **R-isomer** **Structure (2):** - Central carbon with: H, Br, Me, Et, OH - Stereochemistry: Assign priorities - Br(1) > OH(2) > Et(3) > Me(4) - Configuration: **S-isomer** - (1) and (2) are enantiomers ✗ Not superimposable **Structure (3):** - Central carbon with: Me, Br, H, Et, Me, OH - Priorities: Br(1) > OH(2) > Et(3) > Me(4) - Configuration: **S-isomer** ✗ Not the same as (1) **Structure (4):** - Central carbon with: Br, H, Me, HO, Et - Priorities: Br(1) > HO(2) > Et(3) > Me(4) - Configuration: **R-isomer** - Same stereochemistry as (1) ✓ **Superimposable with (1)** ## Conclusion Structures **(1) and (4)** are superimposable because they have: - Identical attachment groups (Br, H, Me, HO, Et) - Same stereochemical configuration (R-isomer) **Answer: (D)**