the long hydrocarbon molecules that make up olive oil only possess weak london dispersion forces between them, yet olive oil is a viscous liquid. how is this possible?
london dispersion forces are strong when molecules contain only c and h atoms.
the regular, repeating shape of hydrocarbon molecules allows them to pack in a crystal structure.
hydrocarbons are more volatile than compounds that contain other kinds of atoms.
the size of the molecules allows for the formation of many weak attractions with other molecules.

The size of the molecules allows for the formation of many weak attractions with other molecules.

Explanation:

Olive is mostly made up of the fatty acid called oleic acid (C18:1) which is a monosaturated omega 9 fatty acid.  

The formula of oleic acid is CH₃(CH₂)₇CH=CH(CH₂)₇COOH

The long hydrocarbon chain of oleic acid allows it to have many weak intermolecular forces along the length of the molecule. The major intermolecular forces acting between long hydrocarbon chains are London dispersion forces.  

pie chart because it is in percents ( % )