Hydrogen chloride gas is a …………… (pure/impure) substance, but when it is dissolved in water then it is a …………… (homogeneous/heterogeneous) mixture.

Rani got a cut on her finger while working in the kitchen. She applied an antiseptic liquid to stop bleeding but it was not effective. Her husband asked her to rub alum on the cut. To her surprise, the bleeding stopped.

(a) Why was the antiseptic liquid not effective ?

(b) What was the use of alum here ?

(c) Who according to you has a proper knowledge of colloidal solutions - Rani or her husband ?

Give an example each for a mixture having the following characteristics :

(a) Two or more coloured constituents soluble in a solvent.

(b) Two immiscible liquids.

Identify colloids from the following :
Copper sulphate solution, milk, smoke, muddy water, butter, sugar solution, face cream, lemonade, jelly, soda water.