<span>Since these molecules are all non-polar, the only intermolecular force of attraction will be London dispersion forces. Since these increase by the size of the molecule, the boiling points will decrease in the same order:
Parafin > Heptadecane > hexane > 2,2-dimethylbutane > propane
For these two, hexane > 2,2-dimethylbutane, dispersion forces are greater in a molecule which is longer and unbranched compared to one which is branched and more compact.</span>
They speed up the breakdown of food in the stomach.
