Question

how electrolysis of water is a chemical change

Answer 1

Because ..here Water which is H2O is break down into H+ and OH- ions..And these cannot be converted to water again...Therfore it is a chemical change..

Answer 2

Water can also undergo a chemical change. Water molecules can be broken down into hydrogen and oxygen molecules by a chemical reaction called electrolysis. When an electric current is passed through liquid water (H2O), it changes the water into two gases—hydrogen and oxygen.