Some anions fall into distinctive categories that are specific to their class of ions. Though additional tests may also be necessary to confirm a specific ion, these distinctive categories offer a valuable first step for determining whether a specific anion is present. Match each anion to the characteristic that is most distinctive for confirming the presence of that anion in solution. The anion forms a volatile weak acid upon addition of strong acid. The anion acts as an oxidizing or reducing agent. The anion forms a precipitate under limited conditions. Answer Bank ci SO2- S2 - Soz - NO3 COZ -