Surface Chemistry - Result Question 3
3. The correct option among the following is
(a) colloidal medicines are more effective, because they have small surface area.
(b) brownian motion in colloidal solution is faster if the viscosity of the solution is very high.
(c) addition of alum to water makes it unfit for drinking.
(d) colloidal particles in lyophobic sols can be precipitated by electrophoresis.
(2019 Main, 10 April II)
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Answer:
Correct Answer: 3. (d)
Solution:
The explanation of the given statements are as follows :
(a) Colloidal medicines are more effective because they (dispersed phase) have larger surface area. Thus, option (a) is incorrect.
(b) Brownian motion of dispersed phase particles in colloidal solution is faster if the viscosity of the solution is very low. Thus, option (b) is incorrect.
(c) Addition of alum $\left(\mathrm{K}_2 \mathrm{SO}_4 \cdot \mathrm{Al}_2\left(\mathrm{SO}_4\right)_3 \cdot 24 \mathrm{H}_2 \mathrm{O}\right)$, an electrolyte to water makes it fit for drinking purposes because alum coagulates mud particles from water.
Thus, option (c) is incorrect.
(d) Precipitation of lyophobic solution particles by electrophoresis is called cottrell precipitation. Thus, option (d) is correct.
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