Question

Non-ideal gases approach ideal behavior at:

• 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 1

The correct option is B high temperature and low pressure

Non-ideal gases approach ideal behavior at a High temperature and low pressure.
At high temperature, V is very large. The terms $\frac{a}{V^2}$ and b can be neglected. The van der Waals' equation reduces to the ideal gas equation.
At low pressure, V is very large and the correction term 'b' can be neglected. At extremely low pressure, the terms $\frac{a}{V^2}$ can be neglected and the van der Waals' equation reduces to the ideal gas equation.