Final answer:
A solution of NaNO₂(aq) is basic due to the presence of the nitrite ion (NO₂¯), which is derived from the weak acid nitrous acid (HNO₂).
Step-by-step explanation:
A solution of NaNO₂(aq) is basic due to the presence of the nitrite ion (NO₂¯). Nitrites are derived from the weak acid nitrous acid (HNO₂), which is a Brønsted-Lowry acid. When dissolved in water, HNO₂ donates a proton to water, forming the nitrite ion and hydroxide ion (OH¯), giving the solution a basic pH.