What type of reaction is this and how do you know?
CaCO3 → CaO + CO2
2H2 + O2 → 2H2O
2K + 2H2O → H2 + 2KOH
CaCO3 + 2HCl → CaCl2 + H2CO3
2KClO3 → 2KCl + 3O2
Ca + 2HCl → CaCl2 + H2
2SO2 + O2 → 2SO3
Pb(NO3 )2 + 2HCl → PbCl2 + 2NHO3
What type of reaction is this and how do you know?
Cu + 2AgNO3 → 2Ag + Cu(NO3 )2
2Na + Cl2 → 2NaCl
CH4 + 2O2 → CO2 + 2H2O
Pb(NO3 )2 + 2KI → PbI2 + 2KNO3
2Fe + O2 → 2FeO
Zn + 2HCl → H2 + ZnCl2

What type of reaction(s) are used above? How do you know?