Answer:
London dispersion forces between octane molecules
Step-by-step explanation:
Water is a polar solvent and the molecules of water are held together by hydrogen bonds.
On the other hand octane is a nonpolar molecule held together only by weak dispersion forces.
We know that the interaction of substances depend on the nature of intermolecular forces present in each substance. As a result, water can not interact with octane because octane molecules predominantly have a different kind of intermolecular force between them- the London dispersion forces.