What is the chemical name for HNO2?

The chemical name for HNO2 is nitrous acid. This compound is an oxoacid, which means it contains hydrogen, oxygen, and another element—in this case, nitrogen. The naming convention for such acids is often based on the number of oxygen atoms present in relation to the more common acid derived from the same element.

In the case of HNO2, it has one fewer oxygen atom than nitric acid, which is HNO3. According to IUPAC naming conventions, when the acid has fewer oxygen atoms than the corresponding more prevalent acid (in this case, nitric acid), the prefix 'nitro' is modified to 'nitrous.' Therefore, HNO2 is specifically named nitrous acid.

The other choices relate to different compounds altogether, which explains why they are not correct. For example, nitric acid refers to HNO3, hydrochloric acid is HCl, and acetic acid is CH3COOH. Each of these has distinct structures and properties that do not match the formula HNO2.