Oxidation-Reduction

  6) (a) 2N₂H₄(g) + N₂O₄(g) 3N₂(g) + 4H₂O(g)

      (b)

              -4  +4        +8  -8                              +2 -2

              -2  +1        +4  -2                     0       +1 -2

           N₂H₄ + N₂O₄ N₂ + H₂O

           N₂O₄ is the oxidizing agent and N₂H₄ is the reducing agent.