Which process best explains why water has a high boiling point compared to other similar-sized molecules?

Water has a high boiling point compared to other similar-sized molecules primarily due to hydrogen bonding. In water (H₂O), each molecule can form up to four hydrogen bonds with neighboring molecules because of its polar covalent structure, which gives rise to a significant dipole moment. The oxygen atom is highly electronegative, attracting electrons more closely than the hydrogen atoms, leading to a separation of charges within the molecule.

When water is heated, a considerable amount of energy is required to break these hydrogen bonds before the molecules can enter the gaseous state. This strong intermolecular force significantly raises the boiling point of water compared to other small molecules like methane (CH₄) or ammonia (NH₃), which do not experience hydrogen bonding to the same extent.

The presence of hydrogen bonding not only enhances water's boiling point but also contributes to other unique properties of water, such as its high specific heat capacity and surface tension. Thus, the prominent role of hydrogen bonding in creating a robust network between water molecules is the key factor explaining its unusually high boiling point among similar-sized molecular compounds.