The combustion of methane (CH4) in the presence of oxygen (O2) produces carbon dioxide (CO2) and water (H2O). The chemical equation for this reaction can be represented as:
CH4 + 2O2 → CO2 + 2H2O
In this reaction, the state symbol for water (H2O) depends on the conditions of the reaction. Under typical combustion conditions, especially in a high-temperature environment, water is often present in the gaseous state as steam. Therefore, the correct state symbol for water in this context would be (g), indicating that it is in the gaseous form.
However, if we consider the post-combustion environment where the products cool down, water may condense into the liquid state. In this case, the state symbol could be (l), representing liquid water. For the purpose of combustion reactions, we usually refer to water in the gaseous state as steam.