Question

The amount of CO formed ______________ as the mixture becomes more and more rich in fuel.

(a) decreases

(b) increases

(c) remains same

(d) none of the mentioned

This question was addressed to me in final exam.

My question is taken from Engine Emissions in section Engine Emissions and their Control of IC Engine

Answer 1

The correct answer is:

(b) increases

As the air-fuel mixture becomes richer in fuel (meaning more fuel relative to air), there is a higher likelihood of incomplete combustion, which leads to an increase in the formation of carbon monoxide (CO). CO is produced when there isn't enough oxygen to fully oxidize the carbon in the fuel, and this becomes more likely with a richer mixture.