Answer
From top to bottom phases: hexane, HDPE, water, PVC, perfluorohexane, Teflon.
Work Step by Step
We need to compare the densities of these substances, and since none of them dissolves in another, each one of them will form their own phase. The phases with lower density will be above those with a bigger density.
Densities in g/cm$^3$:
Hexane- 0.766
HDPE - 0.97
Water - 1.0
PVC - 1.36
Perfluorohexane - 1.669
Teflon - 2.3
