Question

is calcium carbonate a stable carbonate towards heat​

Answer 1

All the carbonates in this Group undergo thermal decomposition to give the metal oxide and carbon dioxide gas. Thermal decomposition is the term given to splitting up a compound by heating it.

All of these carbonates are white solids, and the oxides that are produced are also white solids.

As you go down the Group, the carbonates have to be heated more strongly before they will decompose.

Answer 2

no as  It loses CO2 and becomes calcium oxide (CaO), called “lime” or “quicklime” If treated with water it behaves exothermically and becomes “slaked” lime (as in slaking your thirst), which is a slurry of the mostly indissolved calcium hydroxide and an alkaline solution of it (limewater). Leave it sit around in the air and it will dissolve CO2 and revert back to CaCO3, which when you heat it (return to start). It has its uses based on its alkalinity ( about 12.5 for a saturated solution).