Are atoms the smallest particles we know about, or are there smaller ones?

Substance x has a fixed volume, and the attraction between its particles is strong .substance y had widely spread out particles and can be compressed what can most likely be concluded about these substances

How many moles of air are there in a human lung with a volume of 2.4 l at stp? explain your answer

If anyone would be able to me out with these three questions it would be these are from the chem 2202 course.