Explanation:
Tricalcium aluminate (C₃A) reacts quickly with water and is responsible for the flash setting of cement. Gypsum is added to control the rate of this initial set. Tricalcium silicate (C₃S) provides early strength. Dicalcium silicate (C₂S) gives later strength. Tetracalcium aluminoferrite (C₄AF) contributes to color and hardness. Cement composition is abbreviated in cement chemistry notation.
Explanation:
Iodine sublimes on heating, converting to vapor, leaving sand behind. Iodine vapors can be condensed. Filtration cannot separate two solids; distillation for liquids.
Explanation:
Permanent hardness (due to CaSO₄ etc.) can be removed by adding Na₂CO₃, which precipitates CaCO₃. Boiling only removes temporary hardness. Ion exchange and calgon also work.
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