🔍 Key Concepts

• Behavior of fuel vapors in relation to air (density and movement) • How heated fuel oil behaves differently from fuel at normal temperature • Typical characteristics of flammable/explosive vapors in engine rooms and tank spaces

💭 Think About

• If vapors are flammable and explosive, what does that usually imply about where they tend to collect in an enclosed space? High up near the overhead or low down near the bilge? • Think about emergency procedures: when checking for leaks or dangerous vapors, where are you usually warned to be especially careful—near deck level or near the bottom of compartments? • Which options could you safely rule out based on common sense about what flammable/explosive vapors must NOT be (for example, can such vapors realistically be odorless or non‑toxic in a machinery space?)

✅ Before You Answer

• Verify which statement matches how fuel-oil vapors spread in a compartment (do they sink or rise?). • Eliminate any choice that conflicts with basic safety warnings you’ve heard about working around fuel tanks and bilges. • Confirm that the remaining choice is consistent with fire and explosion hazards described in standard maritime safety training.