So I think the order goes (lowest bp to highest bp) -- 4, 2, 5,1,6,3
this is my reasoning:
#4 is an alkane which is a gas so it's definitely lowest
#2 also has a low bp--> for the haloalkanes- larger atoms means that the electrons are held further away from the nucleus and better able to form bonds with other molecules. Thus, the london forces are greater between molecules of C-C-C-C-Cl than molecules of C-C-C-C-F, that is why C-C-C-C-F has a lower boiling point (the bonds between the molecules are broken at lower temperatures) also Cl is more electronegative and F
#5- forms weak hydrogen bonds, because this molecule only has one protic hydrogen
#1- relatively high boiling point because this molecule strong dipole-dipole interactions between molecules since the molecule is polar
#6- even higher boiling point than #1 because this molecule will form strong hydrogen bonds (it has 2 protic hydrogens that are capable of hydrogen bonding with the other molecules)
#3- honestly i'm not sure why this molecules, boiling point is the highest but I looked it up and it's 114.699 °C i'm guessing it has to do with the fact that it's very polar?
After I reasoned out the order, I went and checked the boiling points and got:
1. 78 deg C
2. 31.9 °C
3. 114.699 °C
4. -1 °C
5. 63 °C
6. 79 °C
Hope that helps, I'm not sure if its totally correct though!