What is a characteristic feature of an ideal gas?

An ideal gas is characterized by the assumption that particles interact only through perfectly elastic collisions. This means that when gas particles collide with each other or with the walls of their container, there is no loss of kinetic energy in the system. Each collision preserves the total energy, which aligns with the ideal gas model that allows for accurate predictions of gas behavior under various conditions.

This concept of perfectly elastic collisions is essential for deriving the behavior of gases using the ideal gas law and other thermodynamic principles. In reality, no gas completely fulfills these conditions, but many approximate these behaviors under certain conditions, particularly at high temperatures and low pressures.

The other options do not accurately define characteristics of an ideal gas. For example, while it is true that an ideal gas occupies a significant amount of volume in reality, the assumption of occupying no volume is a simplification used in ideal gas behavior which isn't true in practice. Also, ideal gases do exert pressure by colliding with the walls of their container, which is a fundamental property of gases. Lastly, while some gases can be liquefied under certain conditions, this is not a feature of ideal gases, as they are typically modeled as being non-interactive and thus cannot be liquefied.