Soda-acid fire extinguisher contains a solution of Sodium hydrogen carbonate and _____?
A) Sulphuric acid
B) Nitric acid
C) Hydrochloric acid
D) None of the above

Hint: Soda acid fire extinguisher is one of the most common fire extinguishers in houses, offices and other places. But this cannot be used for electrical fire accidents. We will study construction, working, and reactions inside this and thus get our answer.

Complete answer:
Construction: It has a strong iron vessel (generally red in colour), which is filled with a solution of sodium bicarbonate/ hydrogen carbonate. It has a side discharge nozzle which is attached to a small glass bottle of Sulphuric acid.
Working: Three important factors are required, for extinguishing fire:
To bring the object which is burning below its ignition temperature.
Extinguishing fire which is going on.
Cutting off the oxygen supply.
All above three things can be achieved by water and carbon dioxide. The reaction can be written as
Reaction taking place:
$2NaHC{O_3} + {H_2}S{O_4} \to N{a_2}S{O_4} + 2{H_2}O + 2C{O_2}$
These are important products after mixing Sodium hydrogen carbonate and sulphuric acid.

Thus, the correct option is (A) Sulphuric acid.

Additional Information Both the products in soda acid fire extinguishers are Water and Carbon dioxide, which are neither combustible nor supports combustion. Due to these properties of them, they are used in soda acid fire extinguishers. It is a good way of extinguishing fire. We should also be careful in case of electrical fires, not to use this as it might cause problems of electric current or Shock to the person who is spraying as water and iron vessels in which these things are kept are good conductors of electric current.

Note: From the above reaction, we can see that the two products water and carbon dioxide, are produced. This carbon dioxide will be in the atmosphere and surrounding the fire, thus we should be careful while using this extinguisher. This type of soda acid fire extinguisher finds a great application, in multi storey buildings, homes, cinema halls.