Question

Which one of the following is a pure substance?

• A. Soft drink
• B. Salt water
• C. Muddy water
• D. Sugar crystals

Answer 1

The correct option is D Sugar crystals

A pure substance consists of only a single type of particle - atoms or molecules. Pure substances are classified as elements and compounds.
Sugar is a pure substance as it is made up of only one kind of molecule which is the sugar molecule.

The other options salt water, muddy water, and soft drink are not pure substances because these are mixtures and contain more than one type of particles.