The process of heating an ore in the absence of air to remove volatile impurities is called:
A. Calcination
B. Roasting
C. Leaching
D. Smelting
Answer: Option A
Solution (By JKExamLibrary)
Calcination involves heating an ore in limited supply or absence of air, often to convert carbonates/hydroxides to oxides and remove moisture or volatile impurities. Example: CaCO₃ → CaO + CO₂; Al(OH)₃ → Al₂O₃ + 3H₂O. Roasting is heating in excess air, usually for sulfide ores. Smelting uses reducing agents to obtain metal. Leaching uses chemicals.
Explanation:
In the titration of a weak acid with a strong base, the equivalence point occurs in the basic region (pH > 7) due to the hydrolysis of the conjugate base formed. Phenolphthalein changes color in the pH range of 8.2 to 10.0, making it the most suitable indicator for detecting this basic equivalence point.
Explanation:
C₂H₅OH + CH₃COOH ⇌ CH₃COOC₂H₅ + H₂O (esterification). Conc. H₂SO₄ acts as catalyst and dehydrating agent. Ethyl ethanoate is an ester with fruity smell.
Explanation:
KBr is ionic; potassium (metal) transfers one electron to bromine (non-metal) forming K⁺ and Br⁻. CO₂ and H₂O are covalent (sharing). Cl₂ is covalent (nonpolar).
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