Which of the following statements are correct ?

Options

A. Z (compressibility factor)for ideal gas is independent of temperature and pressure.
B. Z for ideal gas is greater than one.
C. Z for non-ideal gas is either greater tha one or less than one as well as dependent on temperature and pressure.
D. When `Z gt 1`, then force of attraction dominates over force of replusion.

Explanation

To determine which statements about the compressibility factor (Z) are correct, we will analyze each statement based on the definitions and properties of Z.

### Step-by-Step Solution:

1. **Understanding the Compressibility Factor (Z)**:
- The compressibility factor is defined as \( Z = \frac{PV}{RT} \), where:
- \( P \) = pressure
- \( V \) = volume
- \( R \) = ideal gas constant
- \( T \) = temperature
- For an ideal gas, \( Z \) is equal to 1.

2. **Evaluating Statement A**:
- **Statement A**: "The compressibility factor for an ideal gas is independent of the temperature and pressure."
- Since \( Z \) for an ideal gas is always 1, it does not change with temperature or pressure.
- **Conclusion**: This statement is **correct**.

3. **Evaluating Statement B**:
- **Statement B**: "The Z for an ideal gas is greater than one."
- For an ideal gas, \( Z \) is equal to 1, not greater than 1.
- **Conclusion**: This statement is **incorrect**.

4. **Evaluating Statement C**:
- **Statement C**: "The Z for a non-ideal gas is either greater than one or less than one and depends on the temperature and pressure."
- Non-ideal gases can have \( Z \) values that are either greater than 1 or less than 1, depending on the intermolecular forces and the conditions of temperature and pressure.
- **Conclusion**: This statement is **correct**.

5. **Evaluating Statement D**:
- **Statement D**: "When the Z value is greater than 1, the force of attraction dominates over the force of repulsion."
- This is incorrect because when \( Z > 1 \), it indicates that repulsive forces are dominant, not attractive forces.
- **Conclusion**: This statement is **incorrect**.

### Final Conclusion:
- The correct statements are **A** and **C**.