Question

what test can be done to test if a substance is a colloid?

a. place a magnetic or electric field near the substance to check for conductivity

b. add an acid to see if lumps or fluffy masses form

c. measure the temperature of the substance

d. sift the substance through a large holed sieve

Answer 1

a. place a magnetic or electric field near the substance to check for conductivity

Answer 2

Answer: a. place a magnetic or electric field near the substance to check for conductivity

Explanation: Colloids are solutions which have particle size  between 1 to 1000 nano meters and they can pass through filter paper but not through animal or vegetable membrane.

The colloids form a stable solution as the particles carry similar charge and they keep repelling each other and do not coagulate.

Thus when an electric or magnetic filed is brought near the colloids, the charged particles of colloid are attracted to the oppositely charged electrode and get precipitated.

They can be coagulated by adding oppositely charged electrolyte.