iGCSE Chemistry (0620) Core:11.3 Fuels: Exam Style Questions Paper 1- New Syllabus
▶️ Answer/Explanation
Detailed solution:
Gasoline, also known as petrol, is a fraction obtained from the fractional distillation of petroleum. It consists of hydrocarbon molecules with chain lengths typically in the range of about 5 to 10 carbon atoms. Looking at the options presented, the fuel with molecules in the appropriate chain length range matching the gasoline fraction is option A.
▶️ Answer/Explanation
Detailed solution:
In the fractionating column, the smallest molecules with the lowest boiling points are collected at the top. The order of fractions from lowest boiling point to highest is: refinery gas (lowest), then gasoline, naphtha, kerosene, diesel oil, fuel oil, lubricating oil, and bitumen (highest). Option C correctly lists gasoline → naphtha → kerosene → diesel oil, which is in order of increasing boiling point.
▶️ Answer/Explanation
Detailed solution:
As you go down the fractionating column, the fractions get heavier, with longer chain molecules, higher boiling points, lower volatility, and higher viscosity. Fuel oil is collected lower down than diesel oil, so it has a higher viscosity. Refinery gas is at the top, so it’s more volatile than gasoline. Gasoline is higher than naphtha, so its molecules are shorter. Naphtha is higher than kerosene, so it has a lower boiling point.