What else is present in a fire extinguisher along with ${H_2}SO_4$?

Compound $A$ is prepared by the electrolysis of an aqueous solution of $B$ using a Castner-Kellner cell with mercury as the cathode and carbon as the anode. $A$ and $B$ respectively are:

Which of the following absorbs carbon dioxide and releases oxygen?

The compound which does not exist is

Give the use of hydrated zeolites.

The wire of a flash bulb is made of