Question

Q.3 ) A housewife separates cream from milk by churning it.

Answer 1

(i) Centrifugation is the technique used to separate cream from milk. Milk is a colloid and colloidal particles are not big enough that a filter paper can prevent the particles from passing through it. Hence cream cannot be separated from milk using filter paper.

(ii) The principle is that the when the milk is spun rapidly, the denser particles stay at the bottom and lighter particles stay at the top. Centrifugation is used in diagnostic labs for blood and urine tests as well as in washing machines to squeeze out water from wet clothes.