The melting point of drug \( A(1 S, 2 R) \) is \( 160-165^{\circ} \mathrm{C} \). Compare the melting point range of the drug \( A \) to drug \( B(1 S, 2 S) \) and drug \( C(1 R, 2 S) \). \( A^{\prime}, B \), and \( C \) has identical range. A and \( B \) has identical range, \( A \) and \( C \) has different range. All three drugs have different range. A and \( B \) has different range, \( A \) and \( C \) has same range.

To determine the melting point ranges of drugs \( A \), \( B \), and \( C \), let's analyze their stereochemistry and its impact on their physical properties. ### Given: - **Drug \( A \)**: \( (1S, 2R) \) with a melting point range of \( 160-165^{\circ} \mathrm{C} \) - **Drug \( B \)**: \( (1S, 2S) \) - **Drug \( C \)**: \( (1R, 2S) \) ### Stereochemical Relationships: 1. **Enantiomers**: Molecules that are non-superimposable mirror images of each other. They have identical physical properties, including melting points. 2. **Diastereomers**: Molecules that are not mirror images of each other. They generally have different physical properties, including different melting points. ### Analysis: - **Drug \( A \) and Drug \( C \)**: - **Configurations**: \( A \) is \( (1S, 2R) \) and \( C \) is \( (1R, 2S) \). - **Relationship**: These are **enantiomers**. - **Melting Point**: They will have **identical melting point ranges**. - **Drug \( A \) and Drug \( B \)**: - **Configurations**: \( A \) is \( (1S, 2R) \) and \( B \) is \( (1S, 2S) \). - **Relationship**: These are **diastereomers**. - **Melting Point**: They will have **different melting point ranges**. ### Conclusion: - **A and \( B \)** have **different** melting point ranges. - **A and \( C \)** have the **same** melting point range. **Correct Option:** - **A and \( B \) has different range, \( A \) and \( C \) has same range.** **Answer:** A and B has different range, A and C has same range.