Usually it is found in compound form but can easily as a pure element, just depends on the conditions
K2CO3 is Potassium carbonate.
Copper Carbonate.
Silver = Ag+1 Carbonate = CO3-2 Formula is: Ag2(CO3)
cobalt carbonate
Neither. Pure silver is an element.
Silver bicarbonate or Silver Hydrogen Carbonate.
Ag2CO3
Silver carbonate: Ag2CO3 Silver oxalate: Ag2C2O4
Silver Carbonate
AgHCO3
eggshell is a kind of compound CaCO3 (calcium carbonate)
Assuming it is pure silver, it would be an element.
Silver Nitrate
Calcium Carbonate is a compound as it contains 3 different elements (calcium, carbon and oxygen) that are chemically combined.
Potassium oxide is a compound. Compounds are pure substances that contain more than one type of atom. Since potassium oxide contains potassium and oxygen atoms, it is a compound. Elements are pure substances that contain only one type of atom, such as oxygen gas.
Nickel is a metal. It can be found in a compound as a silicate or carbonate but in its pure form, it is neither. It has many characteristics similar to iron. It is magnetic like iron.