States of matter

Q. A closed flask contains a pure substance, a brown liquid that is at its boiling point. Explain what you are likely to observe in the flask, and distinguish between the inter-particle distances and the average speeds of the particles in the two states present.

hi if a pure substance(brown liquid) is at its boiling point that means the liquid is going through phase transition from a liquid to a gas. you would see vapor above the liquid , the inter-particle distance of the liquid are shorter compared to the gas state and the average speed of particle are slower in liquid state, however the inter-particle distance of the gas are larger and their avg speed are faster.