Question

On mixing a highly soluble impurity in water, the surface tension \(T\) and angle of contact \(\theta\)

• A. decreases and increases respectively
• B. both increase
• C. both decrease
• D. increases and decreases respectively

Hint:

Impurities can significantly alter surface properties of liquids.

Answer 1

The Correct Option is B

Step 1: Effect on surface tension.
Adding a highly soluble impurity increases intermolecular attraction, thereby increasing surface tension.
Step 2: Effect on angle of contact.
With increased surface tension, the liquid tends to wet the surface less, causing an increase in angle of contact.
Step 3: Conclusion.
Both surface tension and angle of contact increase.