Răspuns:
3 C + 2HNO3 → 3CO + 2NO+ H2O
3 C 0 - 6 e - → 3 C II (oxidare) agent reducator
2 N V + 6 e - → 2 N II (reducere) agent oxidant
P 4 + 10 CI2 → 4 P CI 5
4 P 0 - 20 e - → 4 P V (oxidare) agent reducator
20 Cl 0 + 20 e - → 20 Cl -I (reducere) agent oxidant