Which gas is colorless, odorless, and non-combustible, produced during complete fuel combustion?

The correct answer is Carbon Dioxide (CO2) because it is a byproduct of complete combustion, where a carbon-containing fuel reacts with oxygen. This process generates energy, producing carbon dioxide, water vapor, and energy in the form of heat.

Carbon dioxide is indeed colorless and odorless, which are key characteristics of this gas. Unlike carbon monoxide, which is a dangerous product of incomplete combustion, carbon dioxide is non-combustible, meaning it does not support combustion. In complete combustion scenarios, such as in a well-maintained furnace or boiler, CO2 is produced instead of harmful gases, contributing to more efficient fuel use.

Oxygen, while essential for combustion, does not result from the combustion process itself. Instead, it is a reactant that is consumed during combustion. Carbon monoxide is a product of incomplete combustion and is toxic, while methane is a combustible gas that serves as a fuel rather than a product of combustion. This highlights why carbon dioxide is the appropriate answer in the context of complete fuel combustion.