I'm designing a test for a physical chemistry class and I often have trouble wording the questions. This is an example from an old test and I'm curious about the opinions from /sci/. The following questions are related to the phase diagram:

a) If the overall composition of A was 0.4, what is the composition of each of the phases at 100C?
b) Estimate the relative number of moles in each phase (part a)
c) Is it possible to separate A from B by distillation? Why or why not?