The explosive range of petroleum vapors when mixed with air is __________.

Correct Answer: Option B — 1% to 6% by volume

The explosive range, or flammable limits, defines the concentration of vapor in air required for combustion. For most petroleum products, this range is approximately 1% to 6% by volume. Concentrations below 1% are too lean, while those above 6% are too rich to support ignition and flame propagation.