Examples of substances that are not mixtures include:
1. Pure elements: These consist of only one type of atom or molecule. Examples include:
Oxygen (O₂): Composed of only oxygen molecules.
Gold (Au): Composed of only gold atoms.
2. Pure compounds: These are substances made from two or more elements that are chemically bonded in a fixed ratio. Examples include:
Water (H₂O): Composed of hydrogen and oxygen atoms in a 2:1 ratio.
Sodium chloride (NaCl): Composed of sodium and chlorine atoms in a 1:1 ratio.
These examples are not mixtures because they have uniform compositions and distinct chemical properties. Mixtures, on the other hand, involve a combination of different substances that are not chemically bonded and can be separated by physical means.