IIT-JEE 2012 · Paper 1 · Chemistry Q32

ChemistryMultiple correct+4Question 32 of 60

Choose the correct reason(s) for the stability of the lyophobic colloidal particles.

Preferential adsorption of ions on their surface from the solution

Preferential adsorption of solvent on their surface from the solution

Attraction between different particles having opposite charges on their surface

Potential difference between the fixed layer and the diffused layer of opposite charges around the colloidal particles

Answer and worked solution

Official answer: A, D

Lyophobic sols have little affinity for the medium, so they are stabilised by charge, not solvation.

(A) The particles preferentially adsorb a common ion, so all carry the same charge and repel each other. True.
(B) Adsorbing solvent is what stabilises lyophilic sols. False.
(C) Attraction between oppositely charged particles would cause coagulation. False.
(D) The fixed layer and the diffuse layer give the electrical double layer; the potential between them (the zeta potential) keeps particles apart. True.

(A), (D)

Topics:Colloids

IIT-JEE 2012 · Paper 1, Chemistry question 32