Solution:
(a) Zinc carbonate decomposes into zinc oxide and carbon dioxide when heated rapidly in the absence of air.
ZnCO3(s) → ZnO(s) + CO2
(b) Copper metal and sulphur dioxide are formed when copper (I) oxide interacts with copper (I) sulphide.
2Cu2O(s) + Cu2S → 6Cu(s) + SO2(g)