{"knowledge_schema": {"broad_category": "Chemistry \u2192 Stereochemistry \u2192 Optical Activity", "refinement": "This problem involves identifying compounds that possess chirality, which is a key factor in exhibiting optical activity.", "specific_scope": "The focus is on evaluating specific organic compounds to determine which ones are chiral and can rotate plane-polarized light.", "goal": "Identify the number of compounds from the given list that exhibit optical activity."}, "summary": "In this problem, we are tasked with determining which of the provided compounds exhibit optical activity, a property associated with chiral molecules. Optical activity arises from the presence of a chiral center, which is a carbon atom bonded to four different substituents. Among the candidates, (R)-2-butanol is chiral and exhibits optical activity, while meso-tartaric acid and cis-1,2-dichlorocyclohexane are achiral due to their internal symmetry. (S)-1-bromo-2-chloropropane is also chiral and exhibits optical activity. Therefore, the total number of compounds exhibiting optical activity is two: (R)-2-butanol and (S)-1-bromo-2-chloropropane."}