Question

Soda-acid fire extinguisher extinguishes the fire by:
A. cutting the supply of air
B. removing the combustible substance
C. raising the ignition temperature
D. none of these

Answer 1

Hint: Soda-acid fire extinguisher contains sulphuric acid and a solution of sodium hydrogen carbonate. The reaction between sodium bicarbonate and sulphuric acid produces sodium carbonate, water and carbon dioxide.

Complete step by step solution:The fire extinguisher extinguishes the fire in three ways:
The fire extinguisher extinguishes the fire by cutting the supply of air.
The fire extinguisher extinguishes the fire by cooling the combustible substance.
The fire extinguisher extinguishes the fire by cutting the supply of air simultaneously cooling the combustible substance.
Soda-acid fire extinguishers contain sulphuric acid supported on a metallic base with a solution of sodium hydrogen carbonate (baking soda) in a container. Both remain separated before the use. When the cylinder is used as a knob struck at the ground, the sulphuric acid comes into contact with baking soda, the reaction between both taking place and releasing a carbon dioxide gas.
The reaction is as follows:
${{\text{H}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\,{\text{ + }}\,2\,{\text{NaHC}}{{\text{O}}_{\text{3}}}\,\, \to \,{\text{N}}{{\text{a}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}\,{\text{ + }}\,{\text{2}}\,{{\text{H}}_{\text{2}}}{\text{O}}\,{\text{ + }}\,{\text{2}}\,{\text{C}}{{\text{O}}_{\text{2}}}$
The carbon dioxide released in the environment so, the amount of carbon dioxide gas increases in the environment, cuts the supply of air.
So, a soda-acid fire extinguisher extinguishes the fire by cutting the supply of air.

Therefore, option (A) cutting the supply of air, is correct.

Note: Soda-acid fire extinguisher is an example of a carbon dioxide type fire extinguisher. Powder fire extinguisher spray powder of ammonium phosphate. Foam fire extinguisher shows the cooling effect. The foam creates a barrier between the fire and burning fuel. Any fire extinguisher does not remove the combustible substance. They only decrease the cools of the burning substance.