Temperature Dependence MCQ Questions and Answers

1. What happens to the surface tension of a liquid when its temperature is increased?

A. It generally increases

B. It generally decreases

C. It remains exactly constant

D. It first becomes zero and then increases

Correct Answer:
It generally decreases

Explanation:
Surface tension generally decreases as temperature increases because increased thermal motion weakens the effective cohesive forces between surface molecules.

2. At which temperature does the surface tension of a liquid become nearly zero?

A. At its freezing point

B. At room temperature

C. At its critical temperature

D. At its boiling point at atmospheric pressure

Correct Answer:
At its critical temperature

Explanation:
Surface tension approaches zero at the critical temperature because the distinction between the liquid and vapour phases disappears.

3. Which liquid generally has greater surface tension at a lower temperature than at a higher temperature?

A. Water

B. Mercury

C. Alcohol

D. All liquids generally show this trend

Correct Answer:
All liquids generally show this trend

Explanation:
For ordinary liquids, surface tension decreases with an increase in temperature, so it is generally greater at lower temperatures.

4. Why does the surface tension of a liquid decrease when its temperature rises?

A. Molecules become completely stationary

B. Molecular thermal motion increases

C. The liquid changes directly into a solid

D. The mass of each molecule decreases

Correct Answer:
Molecular thermal motion increases

Explanation:
Higher temperature increases molecular thermal motion, reducing the effective cohesive attraction responsible for surface tension.

5. A liquid has a surface tension of 0.075 N/m at 20°C. At 40°C, its surface tension will generally be:

A. Greater than 0.075 N/m

B. Less than 0.075 N/m

C. Exactly 0.075 N/m in every case

D. Always equal to zero

Correct Answer:
Less than 0.075 N/m

Explanation:
Surface tension generally decreases with increasing temperature, so its value at 40°C will normally be less than its value at 20°C.

6. If a liquid is cooled, what generally happens to its surface tension?

A. It decreases

B. It increases

C. It becomes zero

D. It changes into pressure

Correct Answer:
It increases

Explanation:
Cooling reduces molecular thermal motion, allowing cohesive forces to act more effectively and increasing surface tension.

7. The surface tension of a liquid is maximum at which of the following temperatures, assuming the liquid remains in the liquid state?

A. Its highest possible temperature

B. A lower temperature

C. Its critical temperature

D. Any temperature because it is independent of temperature

Correct Answer:
A lower temperature

Explanation:
For a given liquid, surface tension generally becomes larger as temperature decreases, provided the liquid state is maintained.

8. Which statement about the temperature dependence of surface tension is correct?

A. Surface tension usually increases with temperature

B. Surface tension usually decreases with temperature

C. Surface tension is completely independent of temperature

D. Surface tension is always zero above room temperature

Correct Answer:
Surface tension usually decreases with temperature

Explanation:
The usual behavior of liquids is that their surface tension decreases when temperature increases.

9. As the temperature of a liquid approaches its critical temperature, its surface tension generally:

A. Increases without limit

B. Remains unchanged

C. Approaches zero

D. Becomes equal to its density

Correct Answer:
Approaches zero

Explanation:
Near the critical temperature, liquid and vapour become indistinguishable, so the surface tension approaches zero.

10. Two samples of the same liquid are at 15°C and 35°C. Which sample generally has higher surface tension?

A. The sample at 15°C

B. The sample at 35°C

C. Both have exactly the same surface tension

D. Neither sample has surface tension

Correct Answer:
The sample at 15°C

Explanation:
The lower-temperature sample generally has higher surface tension because surface tension decreases as temperature increases.

physics : class11
Temperature Dependence : Surface Tension : Properties of Bulk Matter
MCQ Questions and Answers

Short Questions and Answers

physics : class11Temperature Dependence : Surface Tension : Properties of Bulk Matter MCQ Questions and Answers

Short Questions and Answers

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physics : class11
Temperature Dependence : Surface Tension : Properties of Bulk Matter
MCQ Questions and Answers