Which is not true about carbohydrates?

a. their monomer is a simple sugar.

b. they contain carbon, hydrogen and oxygen.

c. they typically contain hydroxyl groups.

d. they include glycogen and cellulose.

e. they have mostly ionic bonds?

It is not true that carbohydrates have mostly ionic bonds. Carbohydrates actually contain mostly covalent bonds. It is correct, however, that carbohydrates have a simple sugar as a monomer, contain the elements carbon, hydrogen, and oxygen, contain hydroxyl groups, and include glycogen and cellulose.

The last statement "they have mostly ionic bonds" is not true. in formation of polyssacharides from the simple sugars there is release of water molecules. when a molecule of simple sugar reaction with another molecule of simple sugar a water molecule is yielded in this reaction. this reaction is referred to as condensation. the bonds resulting from this type of condensation is referred to as glycosidic bond and not ionic bond.