What is the process of calcination?

• A. Combining water with limestone
• B. Heating limestone
• C. Mixing cement with water
• D. Crushing limestone

Answer: (A)

Calcination is the heating of calcium carbonate (limestone) to drive off carbon dioxide, producing calcium oxide (quicklime). This thermal decomposition occurs in a lime kiln at high temperatures, around 900–1000°C, and it is an endothermic process. The essential reaction is CaCO3 → CaO + CO2. Hydration steps, such as CaO reacting with water to form Ca(OH)2, happen after calcination, not during it. The other actions listed involve adding water to materials, mixing with water, or simply breaking the rock apart—these are not calcination because they do not decompose the carbonate compound.