Question

how state of matter can be changed

Answer 1

there are three states.They are interconversible by evaporation,condensation,fusion,solidification,sublimation

Answer 2

There are three states of matter solid, liquid and gas.Lets say we have some ice it is a solid soon heating it will turn to water which is liquid If we hear the water it will into vapours which are gas.Upon cooling the gas it will turn back to water and upon cooling the water it will turn back to ice.