Which of the following substances will have the highest boiling point? H2OO2Li2OArCH3F

The boiling point of a substance is determined by the type of bonding it has. Here's a step-by-step analysis of each substance:

1. H2O: Water has hydrogen bonding, which is the strongest type of dipole-dipole interaction. This results in a high boiling point.

2. O2: Oxygen is a diatomic molecule with nonpolar covalent bonds. It has a low boiling point because it only has weak London dispersion forces.

3. Li2O: Lithium oxide is an ionic compound. Ionic compounds generally have high boiling points because of the strong electrostatic attraction between ions. However, Li2O is a small molecule, so its boiling point might not be as high as larger ionic compounds.

4. Ar: Argon is a noble gas with a full valence electron shell. It has very weak London dispersion forces and thus a very low boiling point.

5. CH3F: This molecule has dipole-dipole interactions due to the electronegativity difference between carbon, hydrogen, and fluorine. However, these forces are weaker than hydrogen bonding.

In conclusion, H2O (water) will have the highest boiling point because of its strong hydrogen bonding.