Select the intermolecular force(s) present in a liquid sample of each compound.

A) Dispersion forces

The alkanes with atoms of C and H, which have not a substantial diference in electron affinity, do not exhibit regions with more electron density than others.

In this case the only forces that atract one molecule to other are the dispersion forces, which is due to temporal dipoles. Dispersion forces are the weakest intermolecular forces.

b) Dipole - dipole interactions

The double bond C = O of the molecule is highly polar, which creates permanent dipoles and so dipole - dipole interactions.

c) Hydrogen bonding

The large electronegativity difference between H and O create a strong polar bond. The  small hydrogen atom that is slightly positively charge interacts with the unshared electron pairs of oxygens from a close molecule forming hydrogen bonding.

This is the strongest intermolecular force.