Which measurable property becomes constant in water `hArrwater vapour ` equilibrium at constant temperature.

Explanation

To solve the question, "Which measurable property becomes constant in water to water vapor equilibrium at constant temperature?", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Process**:
- The question refers to the equilibrium between liquid water (H2O) and its vapor (water vapor). This is known as the liquid-vapor equilibrium.

2. **Identifying the Phases**:
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