• Pure substance
• Impure substance (mixtures)

1. Pure substance:

      This is a substance which contains a single type of matter. A pure substance has a fixed melting and boiling point.

A pure substance can be an element or a compound.

• An element: it is a pure substance which cannot be broken down into simpler substances by a chemical mean. E.g. oxygen, nitrogen, carbon etc.
• A compound: it is a substance which contains two or more elements chemically combined together. E.g. water (H20)
• Melting point: it s the temperature at which solid changes to liquid. E.g. melting point of ice is 0⁰c.
• Boiling point: it is a temperature at which a liquid boils and becomes vapour (gas)

2. Mixture:

    It is made of two or more types of matter physically joined together.