Question

Why milk is called a colloid give examples

Answer 1

In a colloidal solution, the particles are big enough to scatter a beam of light, and show Tyndall effect. The size of particles in a colloid is bigger than those of a true solution, but smaller than those of a suspension. If a drop of milk is examined under the microscope, we can see small particles of fat floating in liquid. that is why, milk is called a colloidal solution. 
More examples of colloids are coloured gemstones, gelatin, ink etc.

Answer 2

Dear student!

The milk has all the properties of a colloidal solution so milk is a colloid of liquid in liquid and known as an emulsion. Actually, it shows the tyndall effect but since it is very condensed and concentrated solution so the effect is not visible but the protein molecules in milk are of colloidal size and consequently a drop of milk mixed into water will cause a light beam traversing the solution to be scattered.