Final answer:
Oxygen is represented as O₂ in the balanced chemical equation for the reaction of methane with oxygen to produce carbon dioxide and water because oxygen forms diatomic molecules consisting of two oxygen atoms. The option (C) is correct.
Step-by-step explanation:
Oxygen would be represented in the formula equation for the reaction of methane and oxygen to yield carbon dioxide and water as O₂. This is because oxygen exists as a diatomic molecule, meaning two oxygen atoms are bonded together in its most stable form. Consequently, the balanced chemical equation for the combustion of methane (CH₄) with oxygen (O₂) is:
CH₄ + 2O₂ → CO₂ + 2H₂O
The reactants side of the equation contains one methane molecule and two oxygen molecules, while the product side contains one carbon dioxide molecule and two water molecules. This illustrates the principle that in a balanced equation, each element must have the same number of atoms on both the reactant and product sides. Therefore, option (C) is correct.