From weakest to strongest: A, B, C Butanal is an aldehyde which means it has the C=O so it cannot hydrogen bond, only dipole-dipole interactions. However, butanol can hydrogen-bond because of the OH group so it would have the strongest intermolecular force. Pentane would have weakest because it has no electronegative atoms. Solution From weakest to strongest: A, B, C Butanal is an aldehyde which means it has the C=O so it cannot hydrogen bond, only dipole-dipole interactions. However, butanol can hydrogen-bond because of the OH group so it would have the strongest intermolecular force. Pentane would have weakest because it has no electronegative atoms..