 Hexoses exist in two forms, open-chain or cyclic, that easily convert into each other in aqueus solutions.The open-chain form of a hexose, which usually is facoured in solutions, has the general structure H–(CHOH)"n"−1–C(=O)–(CHOH)4−"n"–H, where "n" is 1, 2, or 3.Namely, five of the carbons have one hydroxyl functional group (–OH) each, connected by a single bond, and one has an oxo group (=O), forming a carbonyl group (C=O).