Question

Alum helps in purifying water by

• A. forming Si complex with clay partiles
• B. sulphate part which combines with the dirt and removes it
• C. coagulaing the mud particles
• D. making mud water soluble

Answer 1

Answer: (C)

coagulaing the mud particles

Answer 2

Alum furnishes ${Al^{3+}}$ ions which bring about coagulation of negatively charged clay particles, bacteria etc.