What best defines a perfect gas?

A perfect gas, often referred to in thermodynamics as an ideal gas, is defined by its behavior under various conditions of temperature and pressure. It is characterized by the ability to follow the ideal gas law, which relates pressure, volume, and temperature in a predictable manner.

When a gas is described as being removed from its condensation temperature and remaining gaseous under a specific temperature and pressure, it reflects the conditions under which the gas maintains its state without transitioning into a liquid. This ability aligns with the theory of perfect or ideal gases, where the interactions between gas molecules are minimal, and they do not condense regardless of pressure applied within the limits specified by the ideal gas law.

In contrast, other choices describe characteristics that do not align with the definition of a perfect gas. For instance, a gas that can condense under high pressures or that remains gaseous under all conditions does not fit the ideal gas model since they imply interactions or phase changes that perfect gases do not exhibit. Moreover, stating that a gas does not follow the laws of thermodynamics contradicts fundamental principles; perfect gases indeed adhere to these laws, which underline their ideal behavior under various conditions.