Question

Surface tension of lyophilic sol is

• A. greater than \(H_2O\)
• B. equal to \(H_2O\)
• C. less than \(H_2O\)
• D. none of these

Hint:

Lyophilic sols have strong affinity for the dispersion medium and show properties close to that medium.

Answer 1

The Correct Option is B

Concept:
Lyophilic sols are colloidal solutions in which dispersed particles have strong attraction for the dispersion medium. If the dispersion medium is water, they are called hydrophilic sols. Examples: \[ \text{starch sol},\quad \text{gum sol},\quad \text{gelatin sol} \]

Step 1: Understand lyophilic sol.
The word lyophilic means: \[ \text{liquid-loving} \] So the dispersed phase strongly interacts with the liquid medium. Due to this strong interaction, lyophilic sols are stable.

Step 2: Relation with surface tension.
Lyophilic sols resemble the dispersion medium closely. So their surface tension is nearly equal to that of the dispersion medium. If the medium is water, then surface tension is almost equal to: \[ H_2O \]

Step 3: Check the options.
Option (A) greater than water is not correct.
Option (B) equal to water is the expected answer.
Option (C) less than water is not the standard answer for this question.
Option (D) none of these is incorrect because option (B) is correct. Hence, the correct answer is: \[ \boxed{(B)\ \text{equal to }H_2O} \]