Question

When does a gas behave like perfect gas?
A. At high pressure and high pressure
B. At low pressure and low temperature
C. At high pressure and low temperature
D. At low pressure and high temperature

Answer 1

Hint: In order to answer this question, to know the condition when a gas behaves like perfect gas, we will first explain the respective condition or the correct option and then we will discuss the features or the property of the perfect gas.

Complete answer:
At low pressure and high temperature, a gas behaves like perfect gas or an ideal gas, as the potential energy due to intermolecular forces decreases in comparison to the kinetic energy of the particles, and the size of the molecules decreases in comparison to the empty space between them.

A perfect gas is a theoretical gas model in physics that varies from real gases in ways that simplify those calculations. Intermolecular forces are ignored in ideal gas models. This means that many problems caused by Van der Waals forces can be overlooked. An ideal gas is an example of a perfect gas.

Depending on the field of physics and engineering, the words perfect gas and ideal gas are also interchanged. Other distinctions are often made, such as between thermally perfect and calorically perfect gases, or between imperfect, semi-perfect, and perfect gases, as well as ideal gas characteristics.

Hence, the correct option is D.

Note:Most of the gases behave as perfect gases at low pressures and at very high temperatures. Perfect gas obeys ideal gas law and it has constant specific heats. \[{C_p},{\text{ }}{C_v}\] has constant values. For example if you consider air as perfect gas, \[{C_p} = 1.005{\text{ }}kJ/kg\].