🔍 Key Concepts

• Fire tetrahedron (heat, fuel, oxygen, chemical chain reaction) • Methods of fire extinguishment: cooling, smothering, starvation, interrupting chemical chain reaction • Which substances are normally present in air and which are added as extinguishing agents

💭 Think About

• Think about which element, when taken away, will stop the combustion process itself, not just dilute or cool it • Consider which of the listed options is actually required for a fire to keep burning • Ask yourself: which of these choices is a normal component of the atmosphere that supports combustion?

✅ Before You Answer

• Identify which answer choices are gases used as extinguishing agents versus something the fire actually needs • Recall that air is roughly 21% of one key gas that supports combustion—connect that to the options • Eliminate any option that is not universally necessary for all common fires to burn