Please answer this question 
Dear student,
During whitewash, slaked lime (a mixture of Calcium oxide, CaO + Water, H2O) is used.
CaO + H2O → Ca(OH)2
This calcium hydroxide reacts with carbon dioxide present in the air to form a thin layer of calcium carbonate on the walls, and the water gets evaporated.
This process takes place after two to three days of whitewashing.
Ca(OH)2 + CO2 → CaCO3 + H2O
This formation of calcium carbonate, CaCO3 gives a shiny finish to the walls after two to three days.
Therefore, the assertion is correct but the reason is incorrect.
Hence, the correct option is C.
Regards!
During whitewash, slaked lime (a mixture of Calcium oxide, CaO + Water, H2O) is used.
CaO + H2O → Ca(OH)2
This calcium hydroxide reacts with carbon dioxide present in the air to form a thin layer of calcium carbonate on the walls, and the water gets evaporated.
This process takes place after two to three days of whitewashing.
Ca(OH)2 + CO2 → CaCO3 + H2O
This formation of calcium carbonate, CaCO3 gives a shiny finish to the walls after two to three days.
Therefore, the assertion is correct but the reason is incorrect.
Hence, the correct option is C.
Regards!