Final answer:
Considering the intermolecular forces, NH₃ with its hydrogen bonds has the highest boiling point compared to H₂, N₂, and CH₄, which rely on weaker London dispersion forces.
Step-by-step explanation:
To determine which of the given substances would have the highest boiling point, we should consider the types of intermolecular forces present in each. NH₃ (ammonia) has hydrogen bonding, which is a very strong form of dipole-dipole interaction, because it contains a nitrogen atom directly bonded to hydrogen atoms. Hydrogen bonding generally leads to higher boiling points due to the strong attraction between molecules. Both H₂ (hydrogen) and N₂ (nitrogen) are diatomic molecules with very weak London dispersion forces as their predominant intermolecular force, since they are nonpolar and do not have permanent dipoles. CH₄ (methane) also has London dispersion forces, but because it has more electrons than H₂ and N₂, its London dispersion forces are slightly stronger, leading to a slightly higher boiling point than H₂ or N₂. By comparing the intermolecular forces, we can determine that NH₃ will have the highest boiling point among the given options.