Which is the false statement among the following:

Options

A. Liquids diffuse slowly than gases
B. During evaporation of liquids, heating is always caused
C. Vapour pressure of a liquid increases with rise in temperature
D. Viscosity of liquid decreases with rise in temperature

Answer

To determine which statement among the given options is false, we will analyze each statement one by one.

### Step 1: Analyze the First Statement
**Statement 1:** Liquids diffuse slower than gases.

- **Explanation:** In liquids, particles are closely packed due to stronger intermolecular forces compared to gases, where particles are far apart and move freely. This means that liquid particles collide more frequently, resulting in slower diffusion compared to gases.
- **Conclusion:** This statement is **true**.

### Step 2: Analyze the Second Statement
**Statement 2:** During evaporation of liquids, heating is always caused.

- **Explanation:** Evaporation is a process where molecules at the surface of a liquid gain enough energy to enter the gaseous state. This process actually absorbs heat from the surroundings, resulting in cooling of the liquid. Therefore, it does not cause heating; instead, it causes cooling.
- **Conclusion:** This statement is **false**.

### Step 3: Analyze the Third Statement
**Statement 3:** Vapor pressure of a liquid increases with rise in temperature.

- **Explanation:** As temperature increases, the kinetic energy of the molecules in the liquid also increases. This leads to more molecules escaping into the vapor phase, which increases the vapor pressure.
- **Conclusion:** This statement is **true**.

### Step 4: Analyze the Fourth Statement
**Statement 4:** Viscosity of liquid decreases with rise in temperature.

- **Explanation:** When a liquid is heated, the kinetic energy of its particles increases, which reduces the intermolecular forces of attraction. This results in a decrease in viscosity, as viscosity measures a fluid's resistance to flow.
- **Conclusion:** This statement is **true**.

### Final Conclusion
After analyzing all four statements, we find that the **false statement** is **Statement 2**: "During evaporation of liquids, heating is always caused."

### Summary of the Solution
- **True Statements:** 1, 3, and 4
- **False Statement:** 2