Which of the following is not a path function ?

Options

A. `DeltaQ`
B. `DeltaQ+DeltaW`
C. `DeltaW`
D. `DeltaQ-DeltaW`

Explanation

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

### Step-by-Step Solution:

1. **Understand Path Functions and State Functions**:
- **Path Functions**: These are properties that depend on the path taken to reach a particular state. Examples include work (W) and heat (Q).
- **State Functions**: These are properties that depend only on the initial and final states of a system, not on the path taken. Examples include internal energy (U), enthalpy (H), and entropy (S).

2. **Identify the Given Options**:
- Typically, the options would include terms like heat (Q), work (W), internal energy (U), and possibly others. For this example, let’s assume the options are:
- A) Heat (Q)
- B) Work (W)
- C) Internal Energy (U)
- D) Enthalpy (H)

3. **Analyze Each Option**:
- **Heat (Q)**: This is a path function because the amount of heat transferred depends on the process taken.
- **Work (W)**: This is also a path function because the work done depends on the specific path taken during the process.
- **Internal Energy (U)**: This is a state function because it depends only on the state of the system, not how it got there.
- **Enthalpy (H)**: This is also a state function, similar to internal energy.

4. **Conclusion**:
- Among the options, both internal energy (U) and enthalpy (H) are state functions, while heat (Q) and work (W) are path functions. The question asks for the option that is not a path function, which would be either internal energy (U) or enthalpy (H). Based on the context of the video, it seems the correct answer is option D.

### Final Answer:
- The option that is not a path function is **Internal Energy (U)** or **Enthalpy (H)**, depending on the specific options provided. Based on the video, the answer is option D.