Fuel identification by API gravity Among petrol (gasoline), kerosene, diesel, and furnace oil, which typically has the minimum °API gravity (i.e., is the heaviest on the API scale)?

Introduction / Context:
API gravity is an inverse measure of liquid density relative to water used widely in the petroleum industry. Higher °API indicates a lighter product; lower °API indicates a heavier product. Comparing common fuels helps reinforce typical property ranges.

Given Data / Assumptions:

• Products: petrol (gasoline), kerosene, diesel, furnace oil.
• We seek the product with the minimum API gravity (heaviest).
• Typical commercial ranges are assumed.

Concept / Approach:
From lightest to heaviest by boiling range: gasoline > kerosene > diesel > furnace oil (residual/heavy). Since API decreases with increasing density/heaviness, furnace oil—being a residual/heavy fraction—shows the lowest API among these options.

Step-by-Step Solution:

Verification / Alternative check:
Typical property tables show furnace oil/HSFO with API often well below mid-distillates.

Why Other Options Are Wrong:

• Gasoline, kerosene, diesel: All are lighter than furnace oil and thus have higher API gravities.

Common Pitfalls:
Confusing API with specific gravity directly (they are related but inverse); also mixing up “minimum API” with “lowest density.”

Final Answer:
Furnace oil