Dear Student
The salt is Baking Soda i.e., Sodium bi carbonate.
Na2CO3 + CO2 + H2O → 2NaHCO3
Uses of Baking Soda:
(i) It is used as an antacid as it reduces the acidity in the stomach.
(ii)Due to the formation of soapy foam, it is used in fire extinguishers.
Regards