What is the chemical name for HNO2?

The chemical name for HNO2 is nitrous acid. This compound is an oxyacid that contains nitrogen in a lower oxidation state compared to its counterpart, nitric acid (HNO3), which is a more oxidized form. The nomenclature for such acids is based on the suffixes used to identify their oxidation states: acids formed from anions ending in "-ite," like nitrite (NO2−), are named with the suffix "-ous," hence HNO2 is named nitrous acid.

In contrast, nitric acid, the option listed as "A," corresponds to HNO3, where the nitrogen is in a higher oxidation state, signified by the suffix "-ic." The names in options "C" and "D," hydrochloric acid and acetic acid, refer to totally different compounds: hydrochloric acid is HCl, while acetic acid is CH3COOH. These distinctions in nomenclature and oxidation states are key for correctly identifying the chemical names of acids.