Which gas indicates efficiency? (The higher the level of this gas, the more efficient the engine is operating.)

Question

Quizplus · Accepted Answer

CO (carbon monoxide) is often used as an indicator of combustion efficiency in engines. High levels of CO suggest incomplete combustion, thus lower efficiency. However, in the context of indicating efficiency through lower emissions, a lower level of CO would indicate higher efficiency. The question seems to be formatted incorrectly, leading to confusion. Typically, for efficiency, you'd want lower emissions of CO, indicating more complete combustion.

Which Gas Indicates Efficiency? (The Higher the Level of This