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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3mt217

Which statements about extraction of copper from copper pyrites () and similar ores are correct?

  1. ARoasting converts sulfide to oxide using excess air, evolving
  2. BCalcination is heating in limited or no air, mainly to drive off or water
  3. CSelf-reduction needs no carbon
  4. D is reduced directly by carbon without any prior roasting

Answer: A, B, C

Roasting is done in air and gives oxides and . Calcination drives off volatile matter in limited air. In self-reduction is the reductant for . Sulfides such as ZnS are first roasted to oxides, because carbon reduces oxides more readily and the oxide route is cheaper, so direct reduction of ZnS is not the practice.
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