See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Stereoisomers Classification **Step 1: Understand the definition** Stereoisomers that are **not mirror images** of each other must have a specific relationship—they differ in spatial arrangement at one or more stereocenters, but aren't enantiomers. **Step 2: Eliminate incorrect options** - **(1) Enantiomers**: These ARE mirror images of each other by definition. ✗ - **(3) Tautomers**: These are constitutional isomers involving proton migration and bond rearrangement—not stereoisomers. ✗ - **(2) Mesomers**: This term refers to resonance structures, not stereoisomers. ✗ **Step 3: Identify diastereomers** **(4) Diastereomers** are stereoisomers that: - Have the same molecular formula and connectivity - Differ in stereochemical arrangement at stereocenters - Are **NOT mirror images** of one another **Example:** In a molecule with 2 chiral centers, the (R,R) and (R,S) configurations are diastereomers—they're spatial isomers but not enantiomeric pairs. **Answer: (4) Diastereomers** ✓