Answer: (3) decomposition and melting
Explanation: Chemical change is one in which chemical composition of substance changes.
Physical change is one in which chemical composition of substance do not change.
Freezing is a process in which a liquid changes into solid phase when allowed to cool. Thus it is a physical change.
Melting : It is process in which a solid changes into liquid phase by providing heat. Thus it is a physical change.
Vaporization : It is process in which liquid changes into gaseous phase by providing heat. Thus it is a physical change.
Decomposition is a chemical reaction in which one substance decomposes to form two or more than two products. Thus the chemical composition change, and hence is a chemical change.
Combustion is a reaction in which a substance combines with oxygen gas to produce carbon dioxide, water and a lot of heat. Thus the chemical composition change, and hence is a chemical change.
