Final answer:
Water (H2O) is predicted to have the highest ΔHvap due to its strong hydrogen bonding, which requires more energy to overcome during vaporization compared to the weaker intermolecular forces in SiF4, Cl2, Kr, and H2.
Step-by-step explanation:
To predict which substance has the highest ΔHvap (enthalpy of vaporization), we must consider the type and strength of intermolecular forces present in each. Generally, strong intermolecular forces correspond to higher enthalpies of vaporization, as more energy is required to overcome these forces during the phase change from liquid to gas.
The substances listed are SiF4, H2O, Cl2, Kr, and H2. Among these, H2O has the strongest intermolecular forces due to hydrogen bonding, which is a stronger interaction than dispersion forces present in the other substances. SiF4 would have dipole-dipole interactions and some dispersion forces, but these are weaker than hydrogen bonds. Cl2 and Kr are nonpolar molecules and mainly exhibit dispersion forces, which are weaker than the forces in H2O or SiF4. H2 is also a nonpolar molecule and has the weakest dispersion forces given its very low molar mass.
Considering these points, we conclude that H2O has the highest ΔHvap due to its strong hydrogen bonding interactions.