CH 1. MATTER

Change of liquid to vapour state on heating at constant temperature. It is fast process and produce hotness.

Surface phenomenon i.e. only takes place in surface “Is change of liquid into vapour”. Evaporation has cooling effect. Takes place at all temperatures.

Change of a solid to liquid state at a fixed temperature on absorbing heat.

Change liquid into solid state on cooling at a fixed temperature.

Change of solid in liquid at fixed temperature on heating.

The change of vapour directly into solid on cooling.

Change of solid directly into vapours on absorbing heat.

The force of attraction between the molecules of two different substance is called “FORCE OF COHESION” i.e. between glue and paper.

The inter-molecular force of attraction between the the molecules of the same substance called “FORCE OF COHESION.” i.e. water and water.