Let's solve the question step by step! ## **Step 1: What are Enantiomers?** - **Enantiomers** are a pair of molecules that are **non-superimposable mirror images** of each other. - Each molecule must be **chiral** (have a carbon with four different groups attached). --- ## **Step 2: Analyze Each Pair** ### **Pair A** Structure 1: - Groups: CH₃, H, COOH, HOOC Structure 2: - Groups: COOH, HO, H, CH₃ **Check for chirality:** - Both carbons have 4 different groups attached (chiral). **Are they mirror images?** - Compare the arrangements: The first has COOH and HOOC as groups, but these are the same (carboxylic acid) group, so the carbon is **not chiral** (it has two identical groups). **Conclusion:** *Not enantiomers.* --- ### **Pair B** Structure 1: - Groups: CH₃, H, Br, Cl Structure 2: - Groups: CH₃, H, Br, Cl (but arrangement changed) **Check for chirality:** - Carbon has 4 different groups: CH₃, H, Br, Cl. **Are they mirror images?** - Draw the mirror image: - If you reflect one, the groups swap positions across the plane. - Are they superimposable? - If not, and all groups swap positions correctly, they are enantiomers. Check the arrangement: - In the first, Cl is a wedge (coming out), Br is a dash (going in). - In the second, Br is a wedge, Cl is a dash. - All other groups are the same. **Conclusion:** *These are non-superimposable mirror images.* **They are enantiomers!** --- ### **Pair C** Structure 1: - Groups: CH₂CH₃, H, OH, CH₃ Structure 2: - Groups: CH₂CH₃, H, OH, CH₃ (different arrangement) **Check for chirality:** - Both carbons have 4 different groups. **Are they mirror images?** - Look at the arrangement: In both, OH is a wedge, H is a dash. In the second, arrangement is the same as the first, not swapped like a true mirror image. **Conclusion:** *These are not enantiomers (they are identical or diastereomers).* --- ## **Final Answer** ### **The correct answer is:** **Pair B are enantiomers.** --- ### **Summary Table** | Pair | Are they enantiomers? | |------|:--------------------:| | A | No | | B | **Yes** | | C | No | --- If you have further questions about why B is correct or about chirality, let me know!