Real gases deviate from an ideal behaviour because gas molecules

Options

A. are spherical in shape
B. interact with each other
C. exist freely
D. both 1 and 3

Answer

To solve the question regarding why real gases deviate from ideal behavior, we need to analyze the given options and understand the characteristics of real gases compared to ideal gases.

### Step 1: Understand Ideal Gas Behavior
Ideal gases are hypothetical gases that perfectly follow the gas laws under all conditions. They are assumed to have:
- No volume (point particles)
- No intermolecular forces (no attraction or repulsion between molecules)

### Step 2: Identify Real Gas Characteristics
Real gases, however, do not behave ideally due to several factors:
- They have a finite volume.
- They experience intermolecular forces (attraction or repulsion).
- They do not always follow the ideal gas law, especially at high pressures and low temperatures.

### Step 3: Analyze the Options
1. **Spherical in shape**: While many gas molecules can be approximated as spherical, this does not significantly contribute to deviations from ideal behavior.
2. **Interact with each other**: This is a significant reason for deviation. Real gas molecules experience forces of attraction and repulsion, which affects their behavior.
3. **Exist freely**: This statement is somewhat vague. While gas molecules do move freely, this does not directly relate to deviations from ideal behavior.
4. **Both 1 and 3**: As discussed, the shape and free existence do not primarily cause deviations.

### Step 4: Conclusion
The most relevant reason for real gases deviating from ideal behavior is that they **interact with each other**. Therefore, the correct answer is option **2**.

### Final Answer
Real gases deviate from ideal behavior because gas molecules **interact with each other**.

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