Which one of the following acids is produced in human stomach?

The human stomach produces hydrochloric acid (HCl), which is the primary constituent of gastric acid [1]. This acid is secreted by specialized cells known as parietal cells, located in the gastric pits of the stomach's fundus and body [1]. Hydrochloric acid serves several critical physiological functions: it creates an acidic medium (low pH) that activates the protein-digesting enzyme pepsin, facilitates the breakdown of food, and kills harmful bacteria or microorganisms ingested with food [4]. While the acid is highly corrosive, the stomach lining is protected from damage by a layer of mucus secreted by mucous cells [4]. Other acids like formic, sulphuric, and nitric acids are not naturally produced by the human digestive system. Excessive production of hydrochloric acid can lead to indigestion, which is typically treated with antacids like magnesium hydroxide to neutralize the acidity [1].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 2: Acids, Bases and Salts > pH in our digestive system > p. 27
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > Activity 5.3 > p. 85
3. [4] https://www.ncbi.nlm.nih.gov/books/NBK535425/