Răspuns:
1.
4KI + O2 + 2H2S04 → 2 I 2 + 2K2SO4 + 2H2O
4 I -I - 4 e - → 4 I 0 (oxidare) agent reducator
2 O 0 + 4 e - → 2 O -II (reducere) agent oxidant
2.
2 HNO3 + 3H2S → 3S +2NO + 4H20
3 S -II - 6 e - → 3 S 0 (oxidare) agent reducator
2 N V + 6 e - → 2 N II (reducere) agent oxidant