Question

Aviation fuel for jet aeroplanes is a purified form of which fuel?

• A. Petrol
• B. Kerosene
• C. Gasoline
• D. Diesel

Hint:

Think about which petroleum fraction stays liquid at very low temperatures found at high altitude.

Answer 1

The Correct Option is B

Step 1: Petroleum is separated into different fractions by fractional distillation based on boiling point. One of these fractions, boiling roughly between 150 and 275 degrees Celsius, is kerosene.

Step 2: Jet engines need a fuel that stays liquid and burns steadily even at the very low temperatures found at high altitude, sometimes as low as minus 40 to minus 50 degrees Celsius. Kerosene has a low freezing point and does not gel easily in cold conditions, so a purified and quality controlled version of kerosene, called aviation turbine fuel, is used.

Step 3: Petrol and gasoline are the same fuel under two names, they are lighter and more volatile than kerosene. They catch fire too easily and carry less energy per litre, which makes them unsafe and inefficient for jet engines.

Step 4: Diesel is heavier and thicker than kerosene. At the very cold temperatures of high altitude, diesel becomes waxy and stops flowing properly, so it cannot be used in jet turbines.

Step 5: This confirms that purified kerosene is the correct answer.