Which of the following is not a state function?

Options

A. internal energy
B. temperature
C. work
D. enthalpy

Answer

To determine which of the following is not a state function, we need to understand the concept of state functions and path functions in thermodynamics.

### Step-by-Step Solution:

1. **Define State Functions**:
State functions are properties that depend only on the state of the system, not on how the system reached that state. They are determined by the initial and final conditions of the system.

2. **Examples of State Functions**:
Common examples of state functions include:
- Enthalpy (ΔH)
- Internal Energy (ΔU)
- Entropy (ΔS)

3. **Define Path Functions**:
Path functions, on the other hand, depend on the specific path taken to reach a particular state. They are not solely determined by the initial and final states.

4. **Examples of Path Functions**:
Work (W) and heat (Q) are examples of path functions. The amount of work done or heat transferred can vary depending on the process or path taken.

5. **Identify the Non-State Function**:
From the definitions and examples provided, we can conclude that work (W) is not a state function because it depends on the path taken to perform the work.

6. **Final Conclusion**:
Therefore, the answer to the question "Which of the following is not a state function?" is **Work (W)**.