Final answer:
In the given chemical reaction, CH4 is oxidized to CO2 while oxygen is reduced to H2O.
Step-by-step explanation:
In the given chemical reaction: CH4(g) + 2O2(g) → CO2(g) + 2H2O(g), the oxidation numbers of the elements involved change.
The carbon atom in CH4 goes from an oxidation number of -4 to +4 in CO2, so it is being oxidized. Oxygen goes from 0 in O2 to -2 in H2O, so it is being reduced. The oxidation numbers of hydrogen and oxygen do not change.
Therefore, the reduction reaction is the production of water, and the oxidation reaction is the production of carbon dioxide.