limestone

limestone, that is calcium carbonate, consists of two ions, calcium ion and carbonate ion
You have to test for both ions to see if limestone is present
For calcium ion
We use flame test
Use platinum wire to tip some sample and put it under non-luminous Bunsen burner flame
The flame becomes brick red if calcium ion is present

For carbonate ion
use can add hydrochloric acid to the sample or heat the sample
In both method, a gas will be given out
collect the gas and bubble the gas into limewater
If limewater turns milky, the gas is carbon dioxide
If the gas is carbon dioxide
the sample contains carbonate ion

Combining the two tests, we know whether calcium carbonate, that is limestone, is present