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Three conditions are essential for fire: fuel, oxygen and ignition temperature (the 'fire triangle'). A fire extinguisher works by removing AT LEAST ONE of these. Match the technique to what it removes: Pouring water on a wood fire mainly removes ____ . Pouring CO₂ on an electrical fire mainly removes ____ . Throwing sand on an oil fire mainly removes ____ .
AOxygen / oxygen / heat
BFuel / fuel / fuel
COxygen / heat / fuel
DHeat (cooling) / oxygen / oxygen
Answer & Solution
Correct answer: D. Heat (cooling) / oxygen / oxygen
Water mainly cools the burning material below its ignition temperature (and the steam helps cut off some oxygen too). CO₂ is a heavy gas that blankets the fire, cutting off oxygen. Sand smothers the oil fire — also cutting off oxygen — and is preferred over water because oil floats on water but not on sand.
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