Which of these chemical compounds is NOT found in gastric acid?

The story behind the answer

Sulfuric acid is not found in gastric acid. Stomach acid is predominantly hydrochloric acid (HCl), and gastric secretions also contain chloride salts like sodium chloride (NaCl) and potassium chloride (KCl). These provide chloride ions that combine with hydrogen ions to form HCl. Sulfuric acid (H2SO4) is not produced by the stomach.

Parietal cells in the stomach pump hydrogen ions via the H+/K+ ATPase; chloride follows, yielding HCl that drops stomach pH to about 1–3. This acidic environment denatures proteins, activates pepsin, and kills many microbes. Memory tip: the stomach runs on chloride chemistry—HCl plus NaCl and KCl—while sulfuric acid is “battery acid,” not “belly acid.”