What is the chemical formula of nitric acid?

The chemical formula of nitric acid is HNO3. It shows that each nitric acid molecule contains one hydrogen atom, one nitrogen atom, and three oxygen atoms.

Nitric acid is a strong mineral acid and a powerful oxidizing agent, especially when concentrated. In water, it ionizes readily, producing hydronium ions and nitrate ions. The nitrate ion has the formula NO3−, so nitric acid can be represented in solution as H+ and NO3− in simplified equations, or more accurately as H3O+ and NO3−.

Nitric acid has long been important in chemistry and industry. It is used to manufacture fertilizers, including ammonium nitrate, as well as explosives, dyes, and specialized chemicals. Historically, alchemists called concentrated nitric acid aqua fortis, meaning “strong water.” Mixed with hydrochloric acid, it forms aqua regia, a corrosive mixture capable of dissolving gold.

The wrong options are formulas for other acids: H3PO4 is phosphoric acid, HCl is hydrochloric acid, and H2SO4 is sulfuric acid. The subscript 3 in HNO3 belongs to oxygen, not nitrogen.