Bleaching powder is produced by the action of chlorine on:
A. Gypsum
B. Limestone
C. Quicklime
D. Slaked lime
Answer: Option D
Solution (By JKExamLibrary)
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.
Explanation:
Sodium bicarbonate (NaHCO₃) is an acidic salt because it contains a replaceable hydrogen atom (can neutralize bases). Its aqueous solution is mildly basic due to hydrolysis, but chemically it is an acid salt (formed by partial replacement of H of carbonic acid). K₂SO₄ is normal salt, CaOCl₂ is mixed salt, Na₂CO₃ is normal salt. Acid salts can react with bases.
Explanation:
In reaction C, H₂O₂ oxidizes PbS (black) to PbSO₄ (white), where oxygen atoms from H₂O₂ are added. H₂O₂ itself is reduced to H₂O. In reaction D, H₂O₂ oxidizes I⁻ to I₂; that is also oxidation. But the most straightforward oxidizing reaction among these is the restoration of old paintings (PbS → PbSO₄). Reaction A: H₂O₂ reduces O₃ (acts as reducing agent). Reaction B: H₂O₂ reduces Ag₂O. H₂O₂ can act as both oxidizing and reducing agent.
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