The correct option is Calcium carbonate.
Explanation
The question pertains to the chemical properties of bases, specifically the reaction between a base (calcium hydroxide) and a non-metallic oxide (carbon dioxide). This reaction is chemically similar to a neutralization reaction, resulting in the formation of a salt and water.Detailed Analysis:
- Chemical Identity: Slaked lime is the common name for Calcium Hydroxide, represented chemically as Ca(OH)₂.
- The Reaction: When Calcium Hydroxide reacts with Carbon Dioxide (CO₂), it undergoes a chemical change to form Calcium Carbonate (CaCO₃) and water.
- Chemical Equation:
Ca(OH)₂ (aq) + CO₂ (g) → CaCO₃ (s) + H₂O (l) - Nature of the Product: Calcium Carbonate is a white, insoluble solid. Its formation as a precipitate is what causes lime water to turn "milky" during this reaction. This is also the compound responsible for the shiny finish on walls 2-3 days after whitewashing.
- Analysis of Incorrect Options:
- Calcium oxide (CaO): Known as quick lime, it is the reactant used to produce slaked lime (by adding water), not the product of the reaction with CO₂.
- Calcium sulphate (CaSO₄): This salt is formed when calcium compounds react with sulphuric acid or sulphates, not carbon dioxide.
- Dolomite: This is a double carbonate mineral of calcium and magnesium [CaMg(CO₃)₂], which is not formed in this specific reaction.
Key Takeaway:
The reaction of slaked lime [Ca(OH)₂] with carbon dioxide generates Calcium Carbonate (CaCO₃), an insoluble solid salt.