During white - washing of walls, slaked lime reacts slowly with carbon dioxide in air to form a thin layer of calcium carbonate on the walls. Which of the following reactions represents this correctly?
1
CaO (s) + CO2 (g) → CaCO3 (s)
2
CaO (l) + CO2 (g) → CaCO3 (s)
3
Ca(OH)2 (l) + CO2 (l) → CaCO3 (s) + H2O (l)
4
Ca(OH)2 (aq) + CO2 (g) → CaCO3 (s) + H2O (l)