See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Stereoisomer Analysis To determine which structures are the same stereoisomer, assign priorities using the Cahn-Ingold-Prelog rules and determine R/S configuration. ## Structure 1 - Chiral center with: $Br$, $Cl$, $CH_2CH_3$, $CH_3$ - Priority: $Br(1) > Cl(2) > CH_2CH_3(3) > CH_3(4)$ - Configuration: **R** ## Structure 2 - Chiral center with: $CH_3CH_2(equiv. to CH_2CH_3)$, $Cl$, $Br$, $CH_3$ - Priority: $Br(1) > Cl(2) > CH_2CH_3(3) > CH_3(4)$ - Configuration: **R** ## Structure 3 - Chiral center with: $CH_2CH_3$, $Br$, $Cl$, $CH_3$ - Priority: $Br(1) > Cl(2) > CH_2CH_3(3) > CH_3(4)$ - Configuration: **R** ## Conclusion All three structures have the **same four groups** attached to the chiral center ($Br$, $Cl$, $CH_2CH_3$, $CH_3$) in the **same spatial arrangement** (R configuration). They differ only in how the structure is drawn (different orientations on the page), making them identical molecules. **Answer: (D) 1, 2 and 3**