Question

In a foam type extinguisher, ___________ is present in the bottle.
A.$N{{a}_{2}}C{{O}_{3}}$
B.$A{{l}_{2}}{{(S{{O}_{4}})}_{3}}$
C.$Al{{(OH)}_{3}}$
D.$N{{a}_{2}}S{{O}_{4}}$

Answer 1

Fire extinguishers do not use water, they use carbon dioxide to extinguish fires. The carbon dioxide cuts off the atmosphere from the burning surface, so there is no contact and hence, the fire stops.

Complete step-by-step solution:
-A fire extinguisher is a common device that is used in order to extinguish or control small fires, often in some emergency situations. It's not intended to be used on an out-of-control fire, like one which has reached the ceiling, endangers the user or otherwise requires the expertise of a hearth brigade. Generally, a fireplace extinguisher consists of a cylindrical pressure vessel that is meant to be hand-held that contains an agent which will be discharged to extinguish a fireplace. Fire extinguishers are also manufactured with non-cylindrical pressure vessels but those are very rare.
-There are two main kinds of fire extinguishers: stored-pressure and cartridge-operated. In stored pressure units, the expellant is stored within the same chamber where the firefighting agent is present. Depending on the cause of the fire, different propellants are used. With dry chemical extinguishers, nitrogen is usually used; water and foam extinguishers typically use air. Stored pressure fire extinguishers are the foremost common type. Cartridge-operated extinguishers contain the expellant gas in an exceedingly separate cartridge that's punctured before discharge, thus the propellant exposes to the extinguishing agent. This kind isn't as common, used primarily in areas like industrial facilities, where they receive higher-than-average use. Unlike stored pressure types, these extinguishers use compressed carbonic acid gas rather than nitrogen, although nitrogen cartridges are used on vasoconstrictive (-60 rated) models.
-Now, carbon dioxide is used as a propellant in most of the fire extinguishers. It is so because carbon dioxide is a greenhouse gas, and it absorbs the heat very fast. So, it can cut off the fire from the oxygen present in the air/atmosphere and extinguish the fire permanently. Carbon dioxide can only be obtained from the compound $N{{a}_{2}}C{{O}_{3}}$.

So, our correct answer is option A.

Note: Although there are other greenhouse gases, carbon dioxide is used as it is very cheap in price and easily available too. It is pressurised inside the cylinder so when it comes out, the temperature falls down a lot(as volume increases; pressure decreases) and further helps in extinguishing the fire.