Question

How will be the knocking sound produce in an engine?

(a) Due to an increase in the rate of oxidation of hydrocarbon

(b) Due to a decrease in the rate of oxidation of hydrocarbon

(c) Due to the impurities present in fuel

(d) Due to an increase in the percentile of ethanol molecule

The question was asked in unit test.

Asked question is from Knocking topic in chapter Fuels and Combustion of Engineering Chemistry II

Answer 1

Right answer is (a) Due to an increase in the rate of oxidation of hydrocarbon

Explanation: In the mixture of air and petrol vapour, there occurs a condition when the rate of oxidation increases to such a value that it starts producing sound in the engine which are called a knock. This decreases the octane rating of gasoline.