Question

Knocking in a fuel is

• A. Explosion of unburnt fuel-air mixture
• B. Tendency to spill
• C. Late burning of fuel
• D. Difficult ignition of fuel in combustion chamber

Answer 1

Answer: (A)

Knocking refers to the sensitivity shown by the fuel such as petrol. Due to this, petrol has low pressure and temperature of ignition and tends to ignite before the actual ignition spark in the air. This has deleterious effects on the engine and poses a great risk. To prevent this, the antiknocking agents like methyl tertiary butyl ether, toluene etc. are added to the fuel. These agents increase the temperature and pressure required for ignition.

Hence, the correct answer is 'Explosion of unburnt fuel-air mixture'.