Let's break down the problem step by step: --- ## **Step 1: Understanding Enantiomers** **Enantiomers** are pairs of molecules that are **non-superimposable mirror images** of each other. - They must have a chiral center (a carbon with four different groups attached). - Each group must be arranged in such a way that one structure is the mirror image of the other, and they cannot be superimposed. --- ## **Step 2: Analyze Each Pair** ### **Pair A** - **Left molecule:** - Groups: COOH, H, OH, CH₃ - **Right molecule:** - Groups: COOH, H, OH, CH₃ (different arrangement) Let's check mirror images: If you reflect the first molecule, the groups switch positions but remain attached to the same carbon. Both molecules have four different groups on the chiral carbon. The two structures are **non-superimposable mirror images**. --- ### **Pair B** - **Left molecule:** - Groups: CH₃, H, Br, Cl - **Right molecule:** - Groups: CH₃, H, Br, Cl (different arrangement) Check mirror images: If you reflect the first molecule, Cl and Br swap positions. Both molecules have four different groups on the chiral carbon. The two structures are **non-superimposable mirror images**. --- ### **Pair C** - **Left molecule:** - Groups: CH₂CH₃, H, OH, CH₃ - **Right molecule:** - Groups: CH₂CH₃, H, OH, CH₃ (same arrangement, but OH and H positions swapped) Check mirror images: First molecule and its mirror image (second molecule) have all four groups on the chiral carbon but with the configuration reversed. The two structures are **non-superimposable mirror images**. --- ## **Step 3: Find the Correct Enantiomeric Pair** Let's double-check by looking for **identical groups** (which would make them not enantiomers or diastereomers): - **Pair A:** The two molecules are mirror images and not superimposable. - **Pair B:** Both have four different groups, and arrangements are mirror images. - **Pair C:** Both have four different groups, and arrangements are mirror images. --- ## **Step 4: Verify Configurations** Let's check which pair are **enantiomers** (not identical or diastereomers): - **Pair A:** Both are chiral and mirror images. - **Pair B:** Both are chiral and mirror images. - **Pair C:** Both are chiral and mirror images. But **look closely at the molecular orientation:** - In **Pair A**, the two molecules are true mirror images (classic R/S switch at the chiral center). - In **Pair B**, the two molecules are true mirror images (classic R/S switch at the chiral center). - In **Pair C**, the two molecules are not mirror images, as the groups are not arranged as mirror images (they are actually identical or superimposable). --- ## **Final Answer** ### **Both Pair A and Pair B are enantiomers** **But if you are to choose just one, usually the answer is**: --- ## **Answer:** ### **Pairs A and B are enantiomers. Pair C is not.** --- ### **Summary Table** | Pair | Enantiomers? | |------|:------------:| | A | Yes | | B | Yes | | C | No | --- **If the question expects you to pick one, Pair A is the most typical example. But both A and B are correct as enantiomeric pairs.** --- Let me know if you want a drawing step-by-step for any pair!