Answer: C , The strength of the intermolecular forces between the particles in the liquids.
Explanation:
Since we have 4 boiling flasks with liquids that are at a temp of 20⁰C and out of them all, flask C the has most amount of vapour Particles inside of it, because of that we can conclude that it has the weakest Intermolecular force out of the rest of the boiling flasks since at a temp of 20⁰C it has the most amount of gas particles compared with the other flasks, and not to forget the data in the graph shows us the formula and boiling point of flask C that contains pentane and from that data given we can tell that since the boiling point of pentane Is low then it has to have a weak intermolecular forces, causing it to have more vapour Particles than other flasks, proving the answer to be C since showing the strength of the attraction will explain everything we need to know about flask C and why does it have more vapour Particles than the other flasks.
Note:
(A) is not the answer since all the liquid particles in each flask are in random constant motion at a temp of 20⁰C so it does not justify why flask C has more vapour Particles.
(B) is not the answer since showing the relative speeds of each vapour Particle will not justify why flask C has the most amount of gas particles with the respect of its temperature.
(D) is not the correct answer since we already have data given in the graph about the boiling point of pentane and it's formula so showing the particulate representation is useless.