For a gas deviation from ideal behaviour is maximum at :

Options

A. `0^(@)C` and 1.0 atm
B. `100^(@)C` and 2.0 atm
C. `-13^(@)C` and 1.0 atm
D. `-13^(@)C` and 2.0 atm

Explanation

To determine the conditions under which a gas deviates maximally from ideal behavior, we can analyze the factors that influence gas behavior. Here’s a step-by-step solution:

### Step 1: Understand Ideal Gas Behavior
Ideal gases follow the ideal gas law, which is given by the equation:
\[ PV = nRT \]
where:
- \( P \) = pressure
- \( V \) = volume
- \( n \) = number of moles
- \( R \) = universal gas constant
- \( T \) = temperature

### Step 2: Identify Conditions for Real Gases
Real gases deviate from ideal behavior under certain conditions. Deviations are primarily due to:
- Intermolecular forces (attractive or repulsive)
- Volume occupied by gas molecules

### Step 3: Analyze High and Low Temperatures
- At **high temperatures**, the kinetic energy of gas molecules increases, which minimizes the effects of intermolecular forces. Thus, gases behave more ideally.
- At **low temperatures**, intermolecular forces become significant, leading to greater deviations from ideal behavior.

### Step 4: Analyze High and Low Pressures
- At **low pressures**, gas molecules are far apart, and the volume occupied by the gas molecules becomes negligible compared to the total volume. This also leads to behavior that is closer to ideal.
- At **high pressures**, gas molecules are compressed, and the volume occupied by the gas molecules becomes significant, leading to deviations from ideal behavior.

### Step 5: Combine Conditions
To maximize the deviation from ideal behavior, we need:
- **Low temperature** (to enhance the effects of intermolecular forces)
- **High pressure** (to increase the significance of the volume occupied by gas molecules)

### Conclusion
Thus, the conditions under which a gas deviates maximally from ideal behavior are at **high pressure and low temperature**.

### Final Answer
For a gas, deviation from ideal behavior is maximum at high pressure and low temperature.

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