(a) ZnCO3 is heated in the absence of oxygen?

(b) a mixture of Cu2O and Cu2S is heated?

Answers:

(a) Carbon-di-oxide are liberated

Reaction: ZnCo₃ →ZnO + CO₂

(b) Pure Copper is obtained

Reaction: 2 Cu₂O+ Cu₂S →6Cu+SO₂