Step-by-step explanation:
In physical changes there occurs no change in chemical composition of a substance.
For example, when we cut an apple then we are dividing it into number of parts but we are not changing its chemical composition.
Hence, slicing an apple is a physical change only.
On the other hand, when there occurs change in chemical composition of a substance then it is known as a chemical change.
For example, when sodium is added in an aqueous solution of HCl then it results in the formation of NaCl.
This means that chemical composition of sodium and HCl has changed.