CFCs destroy ozone. Which atom is responsible? MCQ with Answer and Explanation

Explanation:
Thermite reaction: Fe₂O₃ + 2Al → 2Fe + Al₂O₃ + heat. Molten iron produced fills the gap between rails. Aluminium is the reducing agent.

Explanation:
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:
Manganese is extracted by the aluminothermic process (Goldschmidt thermite process) where Mn₃O₄ is reduced by aluminium: 3Mn₃O₄ + 8Al → 9Mn + 4Al₂O₃. This works for metals with less reactivity than Al but not too reactive. Sodium is extracted by electrolysis. Iron is extracted by smelting with coke. Zinc by carbon reduction/electrolysis.