Acid rain affects statues and monuments.
H2O + CO2 → H2CO3
H2CO3 ⇌ 2H+ + CO32-
When pH of the rain drops below 5.6, it is called acid rain.
2SO2 + O2 + 2H2O → 2H2SO4
3NO2 + O2 + 2H2O → 2HNO3
CaCO3 + H2SO4 → CaSO4 + H2O + CO2 (marble)
CaCO3 + 2HNO3 → Ca(NO3)2 + H2O + CO2
