Which one of the following is not a thermodynamical coordinate ?

Options

A. a.Gas constant(R )
B. b.Pressure (P)
C. c.Volume(V )
D. d.Temperature (T)

Explanation

To solve the question "Which one of the following is not a thermodynamical coordinate?", we will analyze the options typically provided in such questions. Common thermodynamic coordinates include pressure (P), volume (V), and temperature (T). We will also consider the gas constant (R) as a potential option.

### Step-by-Step Solution:

1. **Identify Thermodynamic Coordinates**:
- Thermodynamic coordinates are variables that describe the state of a thermodynamic system. The most common thermodynamic coordinates are pressure (P), volume (V), and temperature (T).

2. **Examine the Options**:
- Let's consider the common options: P, V, T, and R (the gas constant).
- P (Pressure) is a thermodynamic coordinate because it can vary in a thermodynamic process.
- V (Volume) is also a thermodynamic coordinate as it can change in various processes.
- T (Temperature) is a thermodynamic coordinate as well since it can vary in different thermodynamic processes.

3. **Evaluate the Gas Constant (R)**:
- The gas constant R is a universal constant that does not change; it is used in equations of state (like the ideal gas law) but does not vary with the state of the system.
- Since R is always constant, it does not serve as a thermodynamic coordinate.

4. **Conclusion**:
- Among the options, R is the only one that does not vary and therefore is not a thermodynamic coordinate. Thus, the answer to the question is R.

### Final Answer:
The option that is not a thermodynamical coordinate is **R (the gas constant)**.

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