Why do Hindus wear white to funerals?

White is associated with spirituality, truth and above all Purity. So, it is somewhat related to all sacred things. Hence all wear white to show respect for the departed on the occasion.

Hindus believe that after a person is dead his soul is at peace and is free from all material and worldly desires. So to represent this idea Hindus wear white to funerals.

BUT, please note that it is not just Hindus that wear White. As part of the common culture in the Indian subcontinent, people from Most Religions wear white to show respect at funerals or other ceremonies.