Any substance changes to another substance that means the change of the physical property. Like water () 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. remains. Thus the chemical property remains fixed when a substance change to other substance.
Glucose and a plants and ur welcome
Acting as a reference point for detecting motion
Rubber it's not a conductor