Which ore is concentrated by froth flotation process?
A. Magnetite
B. Bauxite
C. Galena
D. Carnallite
Answer: Option C
Solution (By JKExamLibrary)
Froth flotation is used to concentrate sulfide ores. Galena (PbS) is a sulfide ore; it is wetted by oil (pine oil) and comes to the surface with froth, while gangue particles wetted by water settle down. Bauxite (Al₂O₃·2H₂O) is an oxide ore concentrated by leaching (Bayer's process). Magnetite (Fe₃O₄) is magnetic ore separated by magnetic separation. Carnallite (KCl·MgCl₂·6H₂O) is a halide ore.
Explanation:
Rhizobium is a nitrogen-fixing bacterium that lives in root nodules of legumes and converts atmospheric N₂ to ammonia, enriching soil fertility naturally. It is a biofertilizer. Urea and ammonium sulfate are synthetic nitrogenous fertilizers. Superphosphate is a synthetic phosphorus fertilizer. Biofertilizers like Azotobacter, Blue-green algae, and mycorrhizae are eco-friendly and sustainable.
Explanation:
Inert electrodes do not participate in the chemical reaction; they merely provide a surface for electron transfer. Platinum and graphite are common inert electrodes. Copper, zinc, and silver are active electrodes and can dissolve or deposit during electrolysis, thereby participating in the chemical change.
Explanation:
CaOCl₂ + 2HCl (dil.) → CaCl₂ + Cl₂ + H₂O. It also releases Cl₂ on reaction with CO₂ in air: CaOCl₂ + CO₂ → CaCO₃ + Cl₂. Water alone hydrolyses it slowly. NaOH does not release Cl₂. The chlorine gas is responsible for bleaching and disinfection.
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