Answer
$H_{2}SO_{3} + H_{2}O → 4H^{+} + SO_{4}^{2-} + 2e^{-}$
This is an oxidation reaction.
Work Step by Step
We add water on the left hand side and H+ to right hand side to balance the equation as it is in acidic medium. Since oxidation state of Sulfur changes from +4 to +6, this is an oxidation reaction.
