UPSC CDS 1 2023 GK Paper

Concept:Soda-acid fire extinguishers work by generating carbon dioxide gas through a chemical reaction, which smothers the fire.Explanation:The extinguisher contains two separate solutions: sodium hydrogen carbonate ($\mathrm{NaHCO}_3$, baking soda) and sulfuric acid ($\mathrm{H}_2\mathrm{SO}_4$).When the extinguisher is inverted or the knob is pressed, the acid mixes with the bicarbonate solution.The reaction is: $2\mathrm{NaHCO}_3 + \mathrm{H}_2\mathrm{SO}_4 \rightarrow \mathrm{Na}_2\mathrm{SO}_4 + 2\mathrm{H}_2\mathrm{O} + 2\mathrm{CO}_2$.The carbon dioxide gas produced builds up pressure, forcing a stream of liquid out of the nozzle.The $\mathrm{CO}_2$ gas forms a blanket over the burning substance, cutting off the supply of oxygen (air).Additionally, the liquid cools the burning material below its ignition temperature.Because both oxygen supply and heat are reduced, the fire is extinguished.Answer:The chemical composition is a solution of sodium hydrogen carbonate and sulfuric acid (Option A).