In P versus V graph, the horizontal line is found in which
_______ exists.

Options

A. Gas
B. Liquid
C. Equilibrium between gas and liquid
D. Super critical temperature.

Explanation

To solve the question regarding the P versus V graph and the conditions under which a horizontal line exists, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the P versus V Graph**:
- A P versus V graph plots pressure (P) on the y-axis and volume (V) on the x-axis. This graph is used to analyze the behavior of substances (like gases and liquids) under different conditions of pressure and volume.

2. **Identifying the Critical Temperature**:
- The critical temperature is the temperature above which a gas cannot be liquefied, regardless of the pressure applied. Below this temperature, gases can be liquefied.

3. **Analyzing Different Regions of the Graph**:
- In the graph, there are different regions:
- Region A: Represents the state of the gas.
- Region B: Represents the transition phase where the gas starts to liquefy.
- Region C: Represents the state where the gas is completely liquefied.
- Region D: Represents the state of the liquid.

4. **Finding the Horizontal Line**:
- The horizontal line in the P versus V graph occurs between points B and C. This line indicates that as pressure is increased, the volume remains constant during the phase transition from gas to liquid. This is because the system is in equilibrium between the gas and liquid phases.

5. **Conclusion**:
- Therefore, the horizontal line in the P versus V graph indicates the **equilibrium between gas and liquid**.

### Final Answer:
The horizontal line in a P versus V graph exists in the region where **equilibrium between gas and liquid** exists.

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