This is a series of chemical reactions starting with calcium carbonate (CaCO3) and ending with carbon dioxide (CO2).

CaCO3 -> CaO + CO2 (Calcium carbonate decomposes to form calcium oxide and carbon dioxide)CaO + 3C -> CaC2 + CO2 (Calcium oxide reacts with carbon to form calcium carbide and carbon dioxide)CaC2 + 2H2O -> C2H2 + Ca(OH)2 (Calcium carbide reacts with water to form acetylene and calcium hydroxide)C2H2 + 2O2 -> 2CO2 + H2O (Acetylene burns in the presence of oxygen to form carbon dioxide and water)

Overall, the reactions can be summarized as:
CaCO3 -> CaO -> CaC2 -> C2H2 -> CO2