Answer
$As_{2}O_{3} (s) + 2NO_{3}^{-} (aq) + 2H_{2}O (l) + 2H^{+} (aq) → 2H_{3}AsO_{4} (aq) + N_{2}O_{3} (aq)$
Oxidizing Agent: $NO_{3}^{-}$
Reducing Agent: $As_{2}O_{3}$
Work Step by Step
We add water and H+ on left hand side to balance the equation as it is in acidic medium. Oxidation state of As is changed from +3 to +5, hence it is oxidized and state of N is changed from +5 to +3, hence it is reduced.
