posted by Jim .
which probably has the lowest boiling point at 1.0 atm pressure.
i was told that the molecule with the lowest weight has the lowest boiling point because it is the least polar as well.
Partly yes and partly no. The molecule likely to have the lowest boiling point will be the one with the lowest molar mass. The polarity plays a VERY important role but it is another factor to consider; i.e., just because a molecule has a low molar mass doesn't mean it is the least polar.