Final answer:
A molecule with the formula CnH2nOn needs to have oxygen bound to every carbon in order to be an unmodified monosaccharide.
Step-by-step explanation:
A molecule with the formula CnH2nOn needs to have oxygen bound to every carbon in order to be an unmodified monosaccharide. Monosaccharides are the simplest form of carbohydrates and serve as the building blocks of complex carbohydrates. Examples of monosaccharides include glucose, fructose, and ribose.