The impurity silica from iron ore is removed by adding: MCQ with Answer and Explanation

Explanation:
Distilled water is produced by boiling water and condensing the steam, leaving behind non-volatile impurities like salts, minerals, and most contaminants. It is almost pure H₂O. Deionized water also has salts removed. However, it may absorb CO₂ and become slightly acidic. It is used in laboratories and batteries.

Explanation:
Thermite: Fe₂O₃ + 2Al → 2Fe + Al₂O₃. Aluminium powder reduces iron oxide, producing molten iron for welding. Al is chosen due to its high reactivity and exothermic reaction.

Explanation:
Bleaching powder is calcium oxychloride, CaOCl₂, made by passing chlorine gas over dry slaked lime (Ca(OH)₂): Ca(OH)₂ + Cl₂ → CaOCl₂ + H₂O. Quicklime is CaO, limestone is CaCO₃, gypsum is CaSO₄·2H₂O. Bleaching powder is used for bleaching cotton and paper, disinfecting water, and as an oxidizing agent. It releases chlorine on exposure to air or acids.