One or more options correct
Regarding the isolation of metals from their ores, choose the correct statement(s).
- A. In the Hall–Héroult process, cryolite is added to alumina to lower the melting point of the electrolytic mixture and to improve its conductivity, and the graphite anode is gradually consumed as and
- B. In the Mond process, impure nickel is converted at about – into volatile , which decomposes at about – to give pure nickel
- C. In the upper, cooler region of a blast furnace, is reduced mainly by solid carbon in direct contact with the ore
- D. In the extraction of copper from copper pyrites, silica is added to convert into slag, and in the Bessemer converter partly formed reacts with to give copper and
Show answer and solution
Answer: A, B, D
A is correct: cryolite lowers the melting point from about K to about K and raises conductivity; oxygen liberated at the carbon anode burns it to /. B is correct: the Mond process uses the reversible formation , forward at low temperature and backward at high temperature. C is incorrect: in the cooler upper zone the reducing agent is (indirect reduction, ), whereas direct reduction by carbon occurs in the hotter lower zone. D is correct: removes iron as slag, and is the self-reduction in the converter. Hence A, B and D.
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