In the reaction oxygen molecules is not balanced on reactant and product side.

2H₂O₂→ H₂O + O₂

Now there are four molecules of hydrogen on reactant side and only two molecules at product side. So total balanced reaction is as follows:

2H₂O₂→ 2H₂O + O₂

It is photolysis reaction as hydrogen peroxide is decomposed in the presence of ultraviolet light to give water and oxygen.