Any substance changes to another substance that means the change of the physical property. Like water ([tex]H_{2}O[/tex]) has different state which changes as the temperature changes. It remain as liquid in the room temperature, in solid form at or below 0°C and vapor phase on or above 100°C. But in all the stage or phase of the substance the composition of the water i.e. [tex]H_{2}O[/tex] remains. Thus the chemical property remains fixed when a substance change to other substance.
