Question

Surface tension of lyophilic sols is:
A) Lower than water
B) More than water
C) Equal to water
D) None of these

Answer 1

Hint:Surface tension is defined as the property of the surface of a liquid that makes it to resist an external force because of the cohesive nature present in the water molecules.
 This is due to the relatively high attraction of water molecules to each other through a network of hydrogen bonds.

Complete answer:
Now let’s understand what Lyophilic Colloids are. When a collide is attracted towards water molecules that means they are Lyophilic (Lyo means solvent and philic means loving). When these colloids are mixed with the favorable liquid, a high force of attraction exists between liquids and colloidal particles that end with the formation of a very stable solution called lyophilic sol.
The surface tension of lyophilic sols is lower compared to the surface tension of water because the lyophilic colloids have a great affinity (attraction) towards the water solvent which decreases the surface tension.
In lyophilic sols particles are heavily hydrated due to which there is an increase in viscosity and increase in viscosity decreases the surface tension.

Hence the correct answer is (A).

Note:Surface tension of any liquid depends on its intermolecular forces. So any factor or property that makes liquid to vary intermolecular forces decides the surface tension of that liquid.