Explanation:

Colloids. Colloids, in chemistry, are a mixture of two substances, in which one substance is divided into minute particles aka colloidal particles (ranging from 1 to 1000 nm in diameter) and dispersed or suspended over another substance. These insoluble particles are inseparable either by filtering or centrifuging. Chemical process known as coagulation. Chemicals (coagulants) are added to the water to bring the nonsettling particles together into larger, heavier masses of solids called floc. Aluminum sulfate (alum) is the most common coagulant used for water purification.