Which process is used to concentrate sulfide ores?
A. Magnetic separation
B. Froth flotation
C. Leaching with NaOH
D. Calcination
Answer: Option B
Solution (By JKSSB Mock Tests)
Froth flotation separates sulfide ore particles from gangue by using oil and water. The ore particles adhere to the froth and float, while gangue sinks. Used for ZnS, PbS, CuFeS₂. Magnetic separation for magnetite, leaching for bauxite.
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:
Cement compounds react with water (hydration) forming hydrated silicates and aluminates, which crystallize and interlock, giving strength. This is exothermic.
Explanation:
Graphite's carbon atoms are arranged in layers held together by weak van der Waals forces. Layers can slide over each other, reducing friction. It is stable at high temperatures, so used where oil would decompose.
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