Give two reasons supporting the idea that sugar is a pure substance and not a mixture.

Sugar is considered a pure substance and not a mixture for two main reasons:

Fixed Chemical Composition: Sugar (sucrose) has a definite chemical formula, C₁₂H₂₂O₁₁, and is made up of only one type of molecule throughout. Every sample of pure sugar contains carbon, hydrogen, and oxygen atoms bonded together in a fixed ratio, which means its composition does not change from one sample to another.

Cannot Be Separated by Physical Means: Sugar is a compound, not a mixture. Its molecules are chemically bonded and cannot be separated into their elements or other substances by physical methods like filtration or evaporation. In contrast, mixtures can be separated by physical processes, but compounds like sugar require chemical reactions to break them down.

Sugar is a pure substance because it has a constant composition and unique chemical structure, unlike mixtures that contain more than one substance and can be separated physically.