Among common refinery fuels—diesel, kerosene, petrol (gasoline), and furnace oil—identify which typically exhibits the lowest flash point (highest volatility).

Introduction:
Flash point is the lowest temperature at which a liquid emits sufficient vapour to form an ignitable mixture near the surface. Lighter, more volatile fuels have lower flash points.

Given Data / Assumptions:

• Compare diesel, kerosene, petrol, and furnace oil.
• Typical refinery specifications and volatility profiles apply.

Concept / Approach:
Volatility order: petrol (most volatile) < kerosene < diesel < furnace oil (least volatile). Therefore, petrol has the lowest flash point among the listed fuels.

Step-by-Step Solution:

Verification / Alternative check:
Standard tables list petrol flash points well below those of kerosene/diesel/furnace oil, consistent with its light distillation range.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing autoignition temperature (intrinsic) with flash point (vapour formation threshold).

Final Answer:
Petrol (gasoline)