Answer
$HNO_2(H^+)$ : Lewis acid
$OH^-$ : Lewis base
Work Step by Step
$HNO_2(aq) + OH^-(aq) N{O_2}^-(aq) + H_2O(l)$
Since $OH^-$ has a free pair of electrons, it acts like a Lewis base, and donnates those electrons to the hydrogen from $HNO_2$, making it
($HNO_2$) a Lewis acid.
