Final answer:
Sugar is a compound known as sucrose, and it cannot be separated into its atomic components through physical means. It forms a homogeneous mixture when dissolved in water, but remains chemically unchanged.
Step-by-step explanation:
Sugar, specifically sucrose with the molecular formula C₁₂2H₂₂2O₁₁1, is a molecular compound. It is made up of carbon, hydrogen, and oxygen atoms joined by chemical bonds. Pure sugar, or sucrose, has a consistent composition of these elements and is characterized by a fixed set of properties such as melting point and sweetness.
When sugar dissolves in water, it forms a homogeneous mixture, also known as a solution. However, the dissolving process does not alter the chemical bonds within each sugar molecule; instead, it merely separates the individual sugar molecules by disrupting the intermolecular forces. Thus, the correct answer is A: Sugar is a compound because its parts cannot be separated through physical means.