Which of the following is not a state function?

Options

A. H
B. U
C. q
D. G

Answer

To determine which of the following is not a state function, we first need to understand the distinction between state functions and path functions.

### Step-by-Step Solution:

1. **Define State Functions and Path Functions**:
- State functions are properties that depend only on the state of the system, not on how that state was reached. Examples include internal energy, enthalpy, entropy, and Gibbs free energy.
- Path functions, on the other hand, depend on the specific path taken to reach a particular state. The two main path functions in thermodynamics are heat (Q) and work (W).

2. **Identify the Given Options**:
- Without the specific options provided in the question, we can still analyze common thermodynamic functions. Let's assume the options include:
- A) Internal Energy (U)
- B) Enthalpy (H)
- C) Work (W)
- D) Gibbs Free Energy (G)

3. **Analyze Each Option**:
- **Internal Energy (U)**: This is a state function as it depends only on the current state of the system.
- **Enthalpy (H)**: This is also a state function, defined as the total heat content of the system.
- **Work (W)**: This is a path function because the amount of work done depends on the path taken to change the state of the system.
- **Gibbs Free Energy (G)**: This is a state function that indicates the maximum reversible work obtainable from a thermodynamic system at constant temperature and pressure.

4. **Conclusion**:
- Among the options analyzed, Work (W) is the only one that is not a state function. Therefore, the correct answer to the question is **C) Work (W)**.