Question

how can milk be a colloid if it doesn't scatter light or show tyndall effect?

Answer 1

Dear student!

Eight types of colloidal systems are possible, depending upon whether the dispersed phase and the dispersion medium are solids, liquids or gases.

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.