Final answer:
Both air and water vapor are gases, which means their particles are too small to be seen. Neither air nor water vapor are exclusively states of water, and they're not liquid or solid.
Step-by-step explanation:
The question 'How do particles of air compare to particles of water vapor?' asks about the states of matter for these substances. Air is a mixture of gases, and water vapor is water in its gaseous state. Therefore, the correct answer to this question is that both are too small to be seen. Particles of air and water vapor are indeed both gases, so they are not liquids or solids and are not states of water exclusively—air includes elements such as nitrogen and oxygen, in addition to possibly containing water vapor.