Answer:

H2O2, also known as hydrogen peroxide, is a powerful oxidizing agent that can be used in both acidic and basic conditions. Because of the release of nascent oxygen, it has the effect of whitening the water.
When the nascent oxygen joins with the coloring matter, it destroys the chemical connections that are present, causing the coloring matter to become oxidized. This results in a reduction in apparent light absorption as well as a whitening of the material.