What occurs when a gas becomes ionized?

When a gas becomes ionized, it gains or loses electrons, leading to the formation of charged particles or ions. This process significantly alters the gas's properties, particularly its conductivity. Ionization typically occurs at high temperatures or when subjected to an external electric field, allowing the ions and free electrons to move freely. This movement of charged particles is what makes the ionized gas conductive, enabling it to carry electrical current more effectively than a non-ionized gas.

In contrast, the other choices do not accurately describe the outcomes of ionization. For instance, while ionization can occur alongside temperature increases, it does not directly cause a gas to become inert or evaporate. Instead, it turns the gas into a state where the electrical conductivity is enhanced, which is particularly important in applications like welding, where the behavior of plasma is crucial.