(a) Solidification : The process of changing liquid into a solid state by cooling is known as solidification.
Example : water → ice.
Condensation : The process of changing a gas or vapour state to a liquid state by cooling is known as condensation.
Example : steam → water.
(b) Melting : The fixed temperature at which a solid changes into a liquid at a given pressure is called its melting point. e.g. ice → water.
Boiling : The fixed temperature at which a liquid starts changing into gaseous state is called its boiling point. e.g. water → steam.
(c) Vapourisation : The process by which a substance changes from a liquid state to vapour state is called vaporisation or evaporation. e.g., Water changes into gaseous state on heating.
Gas : The substance which remain in the gaseous state under normal conditions of temperature and pressure are called gases. e.g, Oxygen, hydrogen, nitrogen.
(d) Miscible: Liquids which mix with each other are called miscible liquids.
Example : Water and alcohol.
Immiscible liquids : Liquids which do not mix with each other are called immiscible liquids. Example Water and oil.