Answer: It does not change the chemical composition of water.
Step-by-step explanation:
A physical reaction is defined as the reaction in which a change in shape, size takes place. No new substance gets formed in these reactions.
There is no change in chemical composition.
Example : melting of ice

A chemical reaction is defined as the reaction in which a change in chemical composition takes place. A new substance is formed in these reactions by breaking of old and making of new bonds.
Example: Oxidation of magnesium leads to formation of white magnesium oxide and is a chemical change.
