The correct name for an aqueous solution of HNO2 is nitrous acid.
Explanation: HNO2 is composed of nitrogen, oxygen, and hydrogen. In chemical nomenclature, HNO2 is specifically referred to as nitrous acid. It is important to distinguish it from other acids like nitric acid (HNO3), which contains one more oxygen atom. The prefix ‘nitrous’ indicates that it has a lower oxidation state of nitrogen compared to nitric acid, which is why ‘nitrous acid’ is the appropriate name for HNO2.