See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

Step 1 - Identify the relationship between the two structures. Examining the two pyranose ring structures, every stereocentre in the left structure has the opposite configuration in the right structure (all wedge bonds become dash bonds and vice versa). This means the two compounds are non-superimposable mirror images of each other, i.e., they are enantiomers. Step 2 - Recall properties of enantiomers. Enantiomers have identical physical properties (melting point, boiling point, solubility, density) and identical chemical properties in achiral environments. They differ in only one measurable bulk property: the direction in which they rotate plane-polarized light. One enantiomer rotates light clockwise (+) and the other rotates it counterclockwise (-) by the same magnitude. Step 3 - Evaluate each option. (a) 'Their chemical and physical properties' - Enantiomers have the same chemical and physical properties in achiral environments, so this is incorrect. (b) 'Nothing' - They do differ in optical rotation, so this is incorrect. (c) 'The direction in which they rotate plane of polarized light' - This is exactly the one property that distinguishes enantiomers. Correct. (d) 'Their interactions with molecules' - Enantiomers interact differently only with other chiral molecules (e.g., enzymes, chiral receptors), but as a general statement of the single defining difference between enantiomers, option (c) is the precise and complete answer. Therefore, the correct answer is C.