Question

С -> СО2 -> СО -> СО2 -> Х -> Са(НСО3) 2

Answer 1

1) C+O2=CO2

2) CO2+H2=CO+H2O

3) CO+H2O=CO2+H2

4) CO2+CaO=CaCO3

5)CaCO3+CO2+H2O=Ca(HCO3)2