UPSC CDS 1 2020 GK Paper

Concept:The human stomach produces hydrochloric acid ($\mathrm{HCl}$) to aid digestion and activate enzymes.Explanation:Parietal cells in the stomach lining secrete hydrochloric acid.This acid creates an acidic environment with a pH of about $1.5$ to $3.5$.$\mathrm{HCl}$ converts the inactive enzyme pepsinogen into active pepsin by supplying $\mathrm{H}^+$ ions.Pepsin then breaks down proteins into smaller peptides.Among the given options, only hydrochloric acid is produced in the human stomach in significant amounts.Formic acid ($\mathrm{HCOOH}$) is found in ant venom, not the stomach.Sulphuric acid ($\mathrm{H}_2\mathrm{SO}_4$) is a strong mineral acid not produced in the body.Nitric acid ($\mathrm{HNO}_3$) is not produced by human cells for digestion.Lactic acid ($\mathrm{C}_3\mathrm{H}_6\mathrm{O}_3$) is produced in muscles during heavy exercise, not in the stomach.Answer:Hydrochloric acid ($\mathrm{HCl}$) is produced in the human stomach.