The chemical name for the compound CuCO3 is Copper (ii) Carbonate.
The number in parentheses after the name of the metal (Copper in this case) represents the oxidation state of the metal ion in the compound. The oxidation state of Copper in Copper (ii) Carbonate is +2, which is indicated by the Roman numeral "ii".
So, the correct name for the compound CuCO3 is Copper (ii) Carbonate.