Chemistry - Real Gas Question with Solution | TestHub

At the critical point the liquid-vapour boundary disappears: the meniscus vanishes, densities and all other physical properties of the two phases become identical, and the "state" can no longer be labelled liquid or gas, so (a), (b), (c) are correct. T_B = a/Rb: easily liquefiable gases have large a (strong attractions), hence higher Boyle temperatures, while gases that are hard to liquefy (small a) have low T_B, so (d) is correct. Hence (a), (b), (c), (d).