Question

Which of the following is not an example of coagulation?

• A. Creaming of milk
• B. Purification of water by alum
• C. Rubber plating and chrome tanning
• D. Formation of delta at the river banks

Answer 1

Answer: (A)

Creaming of milk

For water purification processes, alum acts as a coagulant. A coagulant binds extremely fine and small particles suspended in raw impure water into larger particles that can be removed by filtration and settling. Creaming of milk is not an example of coagulation.
This allows for the removal of unwanted color and cloudiness (turbidity). Butter is a water-in-oil emulsion made from 'cream by phase inversion' (milk as an oil-in-water emulsion, is discussed further on).