Pure substance are the substance that are made up of only one kind of particle and has a fixed or constant structure. For example water, sugar, salt. Pure substance are further classified into elements and compounds.

Characteristics and properties of pure substance are

• Pure substances are mostly homogeneous in nature containing only one type of atoms or molecules.
• These substances mainly have a constant or uniform composition throughout.
• The substances have fixed boiling and melting points.
• A pure substance usually participates in a chemical reaction to form predictable products.

Dear student,

In simple words, a pure substance is a form of matter that has a constant composition and properties that are constant throughout the sample.
Or you can say, The substances that are free from any kind of mixture and contain only one kind of particle are called pure substances.