There is some liquid in a closed bottle. The amount of liquid is continuously decreasing. The vapor in the remaining part

Options

A. (a)must be saturated
B. (b)must be unsaturated
C. (c)may be saturated
D. (d)there will be no vapour.

Answer

To solve the problem, we need to analyze the situation of a closed bottle containing liquid and vapor. Here’s a step-by-step breakdown:

### Step 1: Understand the System
In a closed bottle, we have a liquid and its vapor in equilibrium. This means that molecules from the liquid can escape into the vapor phase (vaporization), and some vapor molecules can return to the liquid phase (condensation).

**Hint:** Consider the processes of vaporization and condensation that occur in a closed system.

### Step 2: Analyze the Given Condition
The problem states that the amount of liquid is continuously decreasing. This implies that more molecules are leaving the liquid phase than are returning from the vapor phase.

**Hint:** Think about what it means for the amount of liquid to decrease in terms of molecular movement.

### Step 3: Determine the Nature of the Vapor
Since the number of molecules leaving the liquid is greater than those returning, this indicates that the vapor cannot be in a saturated state. In a saturated vapor, the rate of vaporization equals the rate of condensation.

**Hint:** Recall the definitions of saturated and unsaturated vapor.

### Step 4: Conclusion
Given that the amount of liquid is continuously decreasing, we conclude that the vapor in the remaining part of the bottle must be unsaturated. Therefore, the correct answer is that the vapor must be unsaturated.

**Hint:** Reflect on the definitions of saturated and unsaturated states in terms of molecular flow.

### Final Answer
The vapor in the remaining part of the closed bottle is **must be unsaturated**.