Question:
How does $\mathrm{H}_{2} \mathrm{O}_{2}$ behave as a bleaching agent?
Solution:
$\mathrm{H}_{2} \mathrm{O}_{2}$ or hydrogen peroxide acts as a strong oxidizing agent both in acidic and basic media.
When added to a cloth, it breaks the chemical bonds of the chromophores (colour producing agents). Hence, the visible light is not absorbed and the cloth gets whitened.