If temperature increases, the surface tension of a liquid

Options

A. increases
B. Decreases
C. Remains the same
D. Increases then decreases

Answer

To solve the question regarding the effect of temperature on the surface tension of a liquid, let's break it down step by step:

### Step 1: Understanding Surface Tension
Surface tension is a property of liquids that arises due to the cohesive forces between liquid molecules. Molecules at the surface experience a net inward force because they are attracted more by the molecules beside and below them than by the air above.

**Hint:** Recall that surface tension is related to the intermolecular forces within the liquid.

### Step 2: Effect of Temperature on Molecules
As the temperature of a liquid increases, the kinetic energy of its molecules also increases. This increase in kinetic energy causes the molecules to move more vigorously.

**Hint:** Think about how temperature affects molecular motion and interactions.

### Step 3: Intermolecular Forces
With an increase in temperature, the increased molecular motion leads to a weakening of the intermolecular forces. The molecules at the surface will experience less cohesive force from the molecules below them compared to when the temperature is lower.

**Hint:** Consider how increased energy can disrupt the attractive forces between molecules.

### Step 4: Conclusion on Surface Tension
Since the cohesive forces between the molecules decrease with increasing temperature, the surface tension of the liquid will also decrease. Therefore, as temperature increases, the surface tension of a liquid decreases.

**Hint:** Remember that a decrease in intermolecular attraction leads to a decrease in surface tension.

### Final Answer
If temperature increases, the surface tension of a liquid decreases.