Which of the following statement is correct ?

Options

A. When `Z gt 1` , real gases are difficult to compress
B. When Z = 1 , real gases are easy to compress
C. When Z = 1 , real gases are easily compressed
D. When `Z gt1` , real gases are easier to compress

Answer

To solve the question, we need to analyze the statements regarding the compressibility factor (Z) of gases and determine which one is correct.

### Step-by-Step Solution:

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

2. **Analyzing the Options**:
- **Option 1**: When Z is greater than 1, real gases are difficult to compress.
- This is true because if Z > 1, it indicates that the gas is experiencing positive deviation from ideal behavior, meaning it has weaker intermolecular forces, making it harder to compress.

- **Option 2**: When Z is equal to 1, real gases are easier to compress.
- This is incorrect. When Z = 1, the gas behaves like an ideal gas, which means it can be compressed, but it does not imply that it is easier to compress than a real gas.

- **Option 3**: When Z is equal to 1, real gases are easily compressed.
- This is also incorrect for the same reason as option 2. Z = 1 indicates ideal behavior, not necessarily easier compression.

- **Option 4**: When Z is greater than 1, real gases are easier to compress.
- This is false. As established, Z > 1 indicates that the gas is difficult to compress.

3. **Conclusion**:
- The only correct statement is **Option 1**: When Z is greater than 1, real gases are difficult to compress.

### Final Answer:
The correct statement is **Option 1**: When Z is greater than 1, real gases are difficult to compress.