Given the task definition and input, reply with output. Given a scientific passage and an answer, generate a question for the given answer.

Passage: If particles have enough kinetic energy to completely overcome the force of attraction between them, matter exists as a gas. The particles can pull apart and spread out. This explains why gases have neither a fixed volume nor a fixed shape. Answer: gas
If particles have enough kinetic energy to completely overcome the force of attraction between them, matter exists as a what?