a. IMFA (intermolecular force of attraction): van der Waal/ London dispersion forces (I'm not sure what you in particular call them, but whichever name you use in class). Higher boiling point would be the one with the stronger van der Waals, which would be the larger molecule...which is C8H18.
b. same The more massive molecule, CH3OCH2, will have the higher boiling point.
c. HOOH or HSSH: in the HOOH there will be hydrogen bonds as well as the London dispersion forces (hydrogen bonds usually involve N, O, or F). In the HSSH molecule, however, no hydrogen bonds exist...there is only a dipole force that happens between polar molecules. There are also Van der Waals (but then, there are always van der waals, so I won't keep saying this, okay?).
For the mere reason that HOOH makes hydrogen bonds and that hydrogen bonds are much stronger than any other intermolecular force, it will be harder for HOOH molecules to overcome that force. Therefore the boiling point will be a lot higher than HSSH.
d) NH2NH2 has hydrogen bonds (as I talked about N, O, and F before; these are the atoms with such strong electronegativity that they form strong intermolecular forces with hydrogen molecules...). CH3CH3 merely has the...you know, I've said it a million times already.
Which one will have the higher boiling point? Take a guess...