this is the question given Section III paper I of IIT JEE 2010. the key are different from one another

Partial roasting of chalcopyrite produces

a. Cu2S and FeO b. Cu2O and FeO

Dear veluri

Sol: CuFeS₂ + O₂ → Cu₂S + 2FeS + SO₂

explanation

The sulphites of copper and iron are partially oxidized
2FeS+ 3O₂ ??→2FeO+ 2SO₂
  2Cu₂ S + 3O₂ ??→2Cu₂ O + 2SO₂

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answer is a)Cu2s and FeO