Are the following materials atoms, molecules, or both?
a. carbon
b. water
c. carbon dioxide
d. nitrogen

A molecule has all valencies covered by molecular (covalent) bonds, leaving no unpaired electrons. A carbon atom needs to form four bonds, and can not be considered a molecule by itself. Buckminsterfullerene, a “sphere” made of sixty carbon atoms, is a molecule completely consisting of carbon atoms.

Explanation:

chemical digestion occurs in the stomach were hcl and pepsin forms chyme, the mouth in which salivary amylase breaks down starch to form bolus, and the small intestine specifically the duodenum.