Place these hydrocarbons in order of decreasing boiling point:

paraffin :
methane:
octane:
isooctane: ( also known as 2,2,4 trimethylpentane)
octadecane:

3 answers

bp increases with increasing mol mass.

So you want them highest molmass to lowest.
paraffin, octadecane, octane, isooctane, methane
paraffin, octadecane, isooctane, pentane, methan