Answer:
Calcium carbonate (CaCO3)
Step-by-step explanation:
Calcium carbonate is a solid base. It is known to decompose at high temperature giving out carbon dioxide as follows;
CaCO3(s)---------> CaO(s) + CO2(g)
The carbon dioxide gas produced is very useful in fire fighting because it smoothers flames.
This reaction only occurs at very high temperature, when a lot of heat has been applied to the system. Hence CaCO3 is a base that can be used in fighting certain kinds of fires.