Questions & Answers

Which gas evolves from fire extinguishers?

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Hint:The fire extinguishers contain different types of chemicals depending on their applications. The handheld fire-extinguishers that are commonly kept in the either homes or offices consist of inert gases or gases that do not support combustion under pressurized conditions.

Complete answer:
The most common types of fire extinguishers contain either nitrogen or carbon dioxide gas under pressurized conditions to propel a stream of the fire-quenching agent to the fire. The active material maybe potassium bicarbonate ${\text{KHC}}{{\text{O}}_{\text{3}}}$, liquid water, or evaporating fluorocarbon or the propelling agent itself which is either carbon dioxide gas or the nitrogen gas. The reason for using carbon dioxide in fire extinguishers is that, when the gas is released from the extinguishers, it looks like dry ice. The cloud of carbon dioxide reduces the oxygen in the air around the fire thereby not allowing the fire to spread. However, this type of extinguishers do not work well outside due to the drift by the wind.

Thus, the correct answer is option A, carbon dioxide.

Carbon dioxide fire extinguishers are mainly used to extinguish fires that are caused by class B substances like flammable liquids and gases and class C or energized electrical fires.
Carbon dioxide does not leave any residue and this is because once it has extinguished the fire, it will dissipate into the air without leaving any residue and no residue means no damage and this is a big advantage over other types of fire extinguishers.