The correct option among the following is:
- (A)Colloidal particles in lyophobic sols can be precipitated by electrophoresis.✓ Correct
- (B)Brownian motion in colloidal solution is faster the viscosity of the solution is very high.
- (C)Colloidal medicines are more effective because they have small surface area.
- (D)Addition of alum to water makes it unfit for drinking.
Answer: (A)
Solution
Lyophobic sols carry a net charge, so under an applied field the particles all drift to the oppositely charged electrode, where they are discharged and come out of suspension. That is exactly what electrophoresis does, which makes it a genuine way to precipitate such a sol. The other claims fail on inspection: Brownian motion is damped, not quickened, by high viscosity; colloidal medicines work because of their large surface area, not a small one; and alum is added precisely to coagulate impurities and make water drinkable.
JEE Main · 2019 · 10 Apr 2019 · Shift 2 · Single correct option