Non-ideal gases approach ideal beheaviour under :

Options

A. high temperature and high pressure.
B. high temperature and low pressure.
C. low temperature and high pressure.
D. low temperature and low pressure.

Answer

To determine the conditions under which non-ideal gases approach ideal behavior, we can analyze the properties of gases and the equations that describe their behavior. Here’s a step-by-step solution:

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

### Step 2: Recognize the Real Gas Equation
For real (non-ideal) gases, the behavior can be described by the van der Waals equation:
\[ \left(P + \frac{a n^2}{V^2}\right)(V - nb) = nRT \]
where:
- \( a \) and \( b \) are constants that account for intermolecular forces and the volume occupied by gas molecules, respectively.

### Step 3: Identify Conditions for Ideal Behavior
Non-ideal gases behave more like ideal gases under certain conditions. These conditions are typically:
- **High Temperature**: At high temperatures, the kinetic energy of gas molecules increases, overcoming intermolecular forces, which makes the gas behave more ideally.
- **Low Pressure**: At low pressures, the volume of the gas is large compared to the volume occupied by the gas molecules themselves. This means that the effects of the volume occupied by the gas molecules (represented by \( b \)) and the intermolecular forces (represented by \( a \)) become negligible.

### Step 4: Conclusion
Thus, the non-ideal gases approach ideal behavior under the conditions of **high temperature and low pressure**.

### Final Answer:
Non-ideal gases approach ideal behavior under **high temperature and low pressure**.

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