Final answer:
Carbon is the atom least likely to act as a hydrogen bond acceptor because it is less electronegative compared to nitrogen, oxygen, and fluorine, and typically does not have the partial negative charge necessary for hydrogen bonds.
Step-by-step explanation:
Among the options given, the atom least likely to act as a hydrogen bond acceptor is carbon (c). Hydrogen bonds are a type of strong dipole-dipole attraction that occurs when a hydrogen atom covalently bonded to a highly electronegative atom, such as nitrogen, oxygen, or fluorine, interacts with a lone pair of electrons on another electronegative atom.
Nitrogen, oxygen, and fluorine have high electronegativities and lone pairs of electrons available, which makes them good hydrogen bond acceptors. In contrast, carbon typically does not form hydrogen bonds because it is less electronegative and does not usually carry the partial negative charge necessary to attract the partially positive hydrogen in a hydrogen bond. Therefore, in the context of hydrogen bonding, carbon is less likely to play the role of an acceptor compared to the other elements listed.