The condensation point of a gas is the temperature at which it changes from a gas to a liquid. For gases that are close to ideal, their behavior is described well by the ideal gas law, which relates the pressure, volume, and temperature of a gas. However, for gases that deviate significantly from ideal behavior, their behavior can be better described by other equations of state.
One way to predict which gases would vary most from being an ideal gas is to look at their critical temperatures and pressures. Gases that have critical temperatures and pressures that are close to their actual temperatures and pressures are more likely to deviate from ideal behavior. Additionally, gases that have strong intermolecular forces, such as hydrogen bonding or dipole-dipole interactions, are more likely to deviate from ideal behavior.
Therefore, if you know the condensation point for a series of gases, you can use this information to predict which gases are more likely to deviate from ideal behavior and which gases are more likely to behave like ideal gases.