What are some examples of change of state of matter?
Solids - Liquid - Gas
One of the easiest examples of change of state can be found in your freezer.
Ice - x < 0 degree celsius
Liquid - x > 0 degree celsius
Gas - x > 100 degree celsius
If you have ice cubes in your freezer and you take them out, they will start melting, because of the room temperature. If you boil water for example in a pressure cooker, the steam that goes out is gas.