A substance with predominantly hydrogen bonding would have a higher boiling point compared to a substance with predominantly London dispersion forces, even if both substances have similar molecular weights.This is because hydrogen bonding is a stronger intermolecular force than London dispersion forces. Stronger intermolecular forces require more energy to overcome, resulting in a higher boiling point for the substance with hydrogen bonding. In contrast, London dispersion forces are weaker and require less energy to overcome, leading to a lower boiling point for the substance with predominantly London dispersion forces.