Answer
$SO_{3}^{2-} (aq) + 2OH^{-} → SO_{4}^{2-} + H_{2}O (l) + 2e^{-}$
Work Step by Step
Since this is a basic solution, we add OH- ion to the left hand side and eater on the right hand side to balance the equation. Since Sulfur is going from oxidation state of +4 to +6, this is an oxidation reaction.
