Carbohydrates contain carbon, hydrogen and oxygen in a characteristic ratio written as:

1. The word carbohydrate means carbon hydrated with water. 2. That description fixes the proportions of the three elements. 3. The ratio is CH2O, one carbon to two hydrogens to one oxygen. 4. The other formulas do not preserve the two-to-one hydrogen to oxygen proportion. _Source: OpenStax Biology for AP(R) Courses (CC BY 4.0), Ch 3 'Biological Macromolecules', sections 3.1-3.5_