Any matter can exist in following states-
1. Solid : A substance whose melting point and boiling points are above room temperature are called solid. Ex: Book, pen, table etc.
2. Liquid : A substance whose melting point is below room temperature and boiling point is above room temperature is called a liquid. Ex: milk, water, honey etc.
3. Gas: A substance whose melting and boiling points are below room temperature is called a gas. Ex: oxygen, hydrogen, nitrogen etc.
4. Plasma : A substance which has a mixture of positively and negatively charged particles or ions is called plasma. The plasma state is formed by superheating of a gas. Ex: Sun etc
5. Bose-Einstein condensate: A substance in which the atoms loose their identity and condensed to form a single super atom is known as BEC. The state is formed by supercooling a substance.
Energy in states of matter : The order of the energy level of the states of matters is as follows:
We know that liquids are obtained by heating solids. Again, gases are obtained by heating liquids. Hence, solids gain energy to be liquid and liquids gain energy to be gas.