🔍 Key Concepts

• Properties of carbon dioxide (CO₂) gas used in fixed fire‑extinguishing systems • Which fire classes CO₂ is normally effective on (e.g., flammable liquids vs. ordinary combustibles) • Hazards to personnel when CO₂ is discharged in an enclosed space

💭 Think About

• For each choice, ask: does this match what you know about how CO₂ behaves physically compared with air? (heavier, lighter, or similar?) • Think about whether CO₂ puts out fire mainly by cooling, by smothering (removing oxygen), or by something else. • Consider whether a total flooding CO₂ release in an enclosed space is safe or dangerous for people still inside.

✅ Before You Answer

• Verify which statement correctly matches a known advantage of CO₂ systems in machinery spaces or flammable‑liquid fires. • Eliminate any choice that describes CO₂ as safe to breathe or harmless in an enclosed space. • Eliminate any choice that claims CO₂ is mainly a cooling agent rather than an oxygen‑displacement/smothering agent.