Which of the following compounds would be best as a hydrogen bond acceptor?

Water serves as an excellent hydrogen bond acceptor due to its highly polar nature and unique molecular structure. In water, the oxygen atom is more electronegative than hydrogen atoms, resulting in a significant dipole moment. This polarity allows water molecules to interact effectively with hydrogen bond donors, where the hydrogen atom of one molecule can form an attraction with the lone pair electrons on the oxygen atom of another.

In this context, hydrogen bonding involves a hydrogen atom covalently bonded to a highly electronegative atom, such as oxygen or nitrogen, being attracted to a lone pair of electrons on another electronegative atom. Water not only can act as a donor in some instances but also has the capability to accept bonds readily due to its two lone pairs of electrons on the oxygen atom.

In contrast, carbon dioxide is a linear molecule that lacks the ability to hydrogen bond effectively because it does not have available electron pairs in a way that can facilitate strong interactions. Methane, being nonpolar and having no highly electronegative atoms, does not participate in hydrogen bonding at all. Hydrogen chloride can act as a hydrogen bond donor, but it is less effective than water at accepting hydrogen bonds because it has only one hydrogen atom and one lone pair on chlorine, limiting its