What is the molecular formula for hydrochloric acid?

HCl

The correct answer is option 4. \(HCl\).

Hydrochloric acid \((HCl\)) is a chemical compound composed of one hydrogen atom \((H)\) and one chlorine atom \((Cl)\). It is a colorless, highly acidic solution with a sharp, pungent odor. In its pure form, it is a gas, but it is typically dissolved in water to form a solution known as hydrochloric acid.

When dissolved in water, hydrogen chloride \((HCl)\) molecules dissociate into hydrogen ions \((H^+)\) and chloride ions \((Cl^-)\). This dissociation process makes hydrochloric acid a strong acid. The hydrogen ions contribute to the acidity of the solution by donating protons to other substances, while the chloride ions remain as spectator ions.

The reaction of hydrochloric acid with water can be represented as follows:

\(HCl + H_2O \longrightarrow H_3O^+ + Cl^-\)

In this equation, \(H_3O^+\) represents the hydronium ion, which is formed when a water molecule gains a proton from the hydrogen chloride molecule.

Hydrochloric acid is widely used in various industrial processes, laboratory experiments, and as a household cleaner. It is also produced naturally in the stomach, where it plays a crucial role in digestion by helping to break down food and kill ingested bacteria.