The properties that can be observed and specified like colour, hardness, rigidity, fluidity, density, melting point, boiling point etc. are the physical properites.
The interconversion of states is a physical change because these changes occur without a change in composition and no change in
the chemical nature of the substance.
Although ice, water and water vapour all look different and display different physical properties, they are chemically the same.
Both water and cooking oil are liquid but their chemical characteristics are different.
They differ in odour and inflammability. We know that oil burns in air whereas water extinguishes fire. It is this chemical property of oil that makes it different from water. Burning is a chemical change. During this process one substance reacts with another to undergo a change in chemical composition. Chemical change brings change in the chemical properties of matter and we get new substances. A chemical change is also called
a chemical reaction.
During burning of a candle, both physical and chemical changes take place.