Question

what is the chemical that refluxes into the esophagus, causing the burning pain of gerd?
bile
hydrochloric acid (hcl)
saliva
mucus

Explanation:

Gastro - esophageal reflux disease (GERD) occurs when the lower esophageal sphincter does not close properly, allowing stomach contents to flow back into the esophagus. Hydrochloric acid, which is highly acidic and present in the stomach for digestion, is the main chemical that causes the burning pain when it refluxes into the esophagus. Bile can also be involved in some cases but is less common as the primary cause of the burning pain. Saliva and mucus are not the chemicals responsible for the burning pain in GERD.

Answer:

Hydrochloric acid (HCl)