Concepts to understand before solving:
-Oxygen is ALWAYS reduced
-OIL- Oxidation Is Loss of electrons
-RIG- Reduction Is Gain of electrons
-the element that is oxidized is the reducing agent
-the element that is reduced is the oxidizing agent
A. 2H2 + O2 —> 2H2O
O is reduced, making it the oxidizing agent
H is oxidized, making it the reducing agent
B. 2KNO3 —> 2KNO2 + O2
O is reduced, making it the oxidizing agent
KNO is oxidized, making it the reducing agent