For a given mass of gas isobar is the graph drawn between

Options

A. P and volume at constant T
B. T and P at constant V
C. T and V at constant P
D. P and `(1)/(V)` at constant T

Answer

To solve the question regarding the graph that represents an isobar for a given mass of gas, we will analyze each option step by step.

### Step-by-Step Solution:

1. **Understanding Isobar**:
- An isobar is defined as a process or condition where the pressure remains constant. Therefore, we need to find a graph that depicts this condition.

2. **Analyzing Option A (Pressure vs. Volume at Constant Temperature)**:
- This graph represents an isotherm because the temperature is kept constant. According to the ideal gas law (PV = nRT), if the temperature is constant, pressure and volume are inversely related. Therefore, this graph does not represent an isobar.

3. **Analyzing Option B (Temperature vs. Pressure at Constant Volume)**:
- This graph represents an isochoric process since the volume is constant. According to the ideal gas law, at constant volume, pressure is directly proportional to temperature (P ∝ T). Hence, this graph does not depict constant pressure and is not an isobar.

4. **Analyzing Option C (Temperature vs. Volume at Constant Pressure)**:
- This graph represents an isobar because the pressure is kept constant. According to the ideal gas law, at constant pressure, volume is directly proportional to temperature (V ∝ T). Thus, this graph correctly represents an isobar.

5. **Analyzing Option D (Pressure vs. 1/V at Constant Temperature)**:
- This graph represents an isotherm since the temperature is constant. According to the ideal gas law, at constant temperature, pressure is inversely proportional to volume (P ∝ 1/V). Therefore, this graph does not represent an isobar.

### Conclusion:
After analyzing all the options, we conclude that the correct answer is **Option C: The graph between temperature and volume at constant pressure is an isobar**.