Which gas is colorless, odorless, nonflammable, produced by combustion, and is familiar to firefighters as an inert extinguishing agent in hand portable extinguishers?

Which gas is colorless, odorless, nonflammable, produced by combustion, and is familiar to firefighters as an inert extinguishing agent in hand portable extinguishers?

• A. CO
• B. CO2
• C. SO2
• D. HCl

Answer: (B)

The key idea is identifying a gas that suits extinguishing without promoting combustion and can be delivered from a portable extinguisher. Carbon dioxide fits perfectly: it is colorless, odorless, nonflammable, and a byproduct of combustion. When released from a hand-portable extinguisher, CO2 blankets the fire and displaces oxygen, cooling the fuel surface and starving the flame of the oxygen it needs. This makes it a familiar inert extinguishing agent in portable units, especially for small electrical fires or enclosed spaces. Other gases listed don’t fit the same role: carbon monoxide is also produced by combustion and is toxic and flammable, not used as an extinguishing agent; sulfur dioxide and hydrogen chloride are pungent, corrosive, and not suitable inert extinguishing agents.

The key idea is identifying a gas that suits extinguishing without promoting combustion and can be delivered from a portable extinguisher. Carbon dioxide fits perfectly: it is colorless, odorless, nonflammable, and a byproduct of combustion. When released from a hand-portable extinguisher, CO2 blankets the fire and displaces oxygen, cooling the fuel surface and starving the flame of the oxygen it needs. This makes it a familiar inert extinguishing agent in portable units, especially for small electrical fires or enclosed spaces. Other gases listed don’t fit the same role: carbon monoxide is also produced by combustion and is toxic and flammable, not used as an extinguishing agent; sulfur dioxide and hydrogen chloride are pungent, corrosive, and not suitable inert extinguishing agents.