Which of the following is/are state function?

Options

A. Enthalpy
B. Heat
C. Entropy
D. Gibb's fre energy (G)

Explanation

To determine which of the given options are state functions, we need to understand the definition of a state function and analyze each option accordingly.

### Step-by-Step Solution:

1. **Define State Function**:
A state function is a property of a system that depends only on its current state, not on how it reached that state. Examples include temperature, pressure, volume, enthalpy, internal energy, entropy, and Gibbs free energy.

**Hint**: Remember that state functions are determined by the state of the system and not the path taken to reach that state.

2. **Analyze Each Option**:
- **Enthalpy (H)**: Enthalpy is a measure of the total heat content of a system. It is a state function because it depends only on the state of the system (initial and final states) and not on the path taken.

**Hint**: Consider how enthalpy is defined and whether it changes based on the process path.

- **Heat (q)**: Heat is a form of energy transfer that depends on the path taken during a process. It is not a state function because it varies with the specific process followed.

**Hint**: Think about whether heat can be determined solely by the initial and final states of a system.

- **Entropy (S)**: Entropy is a measure of the disorder or randomness of a system. It is a state function because it depends only on the state of the system and not on how that state was reached.

**Hint**: Reflect on how entropy relates to the distribution of energy in a system.

- **Gibbs Free Energy (G)**: Gibbs free energy is defined as G = H - TS (where T is temperature and S is entropy). Since both enthalpy and entropy are state functions, Gibbs free energy is also a state function.

**Hint**: Consider the components of Gibbs free energy and whether they are state functions.

3. **Conclusion**:
Based on the analysis:
- Enthalpy (H) is a state function.
- Heat (q) is not a state function.
- Entropy (S) is a state function.
- Gibbs Free Energy (G) is a state function.

Therefore, the state functions among the options given are **Enthalpy, Entropy, and Gibbs Free Energy**.

### Final Answer:
The state functions are: Enthalpy, Entropy, and Gibbs Free Energy.