The dominant intermolecular force between acetone molecules is dipole-dipole forces.
Acetone (C3H6O) is a polar molecule due to the presence of a carbonyl group (C=O) which creates a permanent dipole. Each acetone molecule has a partial negative charge at the oxygen atom and a partial positive charge at the carbon atoms. This polarity facilitates dipole-dipole interactions, where the positive end of one acetone molecule attracts the negative end of another. While acetone does exhibit some London dispersion forces due to its molecular size, they are significantly weaker than the dipole-dipole attractions in this case.
Hydrogen bonding is not the primary interaction in acetone, as it lacks the necessary hydrogen atoms bonded to highly electronegative atoms like nitrogen, oxygen, or fluorine. Ion-dipole forces are typically seen in interactions between ions and polar molecules, which is not applicable here. Therefore, among the given options, dipole-dipole forces are the most significant in acetone interactions.