Question

The surface tension of most of the liquid decreases with rise in

• A. viscosity of the liquid
• B. diameter of capillary
• C. temperature of the liquid
• D. density of the liquid

Hint:

Remember: Surface tension \(\propto \frac{1}{T}\) approximately. Higher temperature → lower surface tension. This is why hot water cleans better.

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
We need to identify the factor with which surface tension of most liquids decreases when that factor increases.

Step 2: Key Formula or Approach:
Surface tension arises from cohesive forces between molecules. As temperature increases, molecular thermal agitation increases, weakening cohesive forces, hence surface tension decreases.

Step 3: Detailed Explanation:
Viscosity, capillary diameter, and density do not directly cause a systematic decrease in surface tension with their rise. Temperature is well known to reduce surface tension for most liquids.

Step 4: Final Answer:
Thus surface tension decreases with rise in temperature, option (C).