Question 67

The Correct Answer is B **Explanation of B (below the "explosive range"):** The term "lean" (in the context of combustion or explosion) refers to a mixture where the fuel concentration is too low relative to the oxidizer (usually air or oxygen) to sustain a rapid combustion event like an explosion. Explosive materials have an "explosive range" (also known as the Flammability Limits or Explosive Limits, defined by the Lower Explosive Limit/Lower Flammability Limit (LEL/LFL) and the Upper Explosive Limit/Upper Flammability Limit (UEL/UFL)). If a mixture is described as "too lean to explode," it means the fuel concentration is less than the minimum required concentration (the LEL/LFL). Therefore, the mixture is below the lower boundary of the explosive range. **Explanation of Incorrect Options:** **A) above the "explosive range":** If a mixture were above the explosive range (meaning the fuel concentration is greater than the UEL/UFL), it would be described as "too **rich**" to explode, not "too lean." **C) within the "explosive range":** If the cargo was within the explosive range, it would be capable of exploding (provided an ignition source was present). The statement explicitly says the cargo is "too lean **to explode**," meaning it is outside this range. **D) None of the above:** Option B accurately describes the condition of a mixture that is "too lean."