Question

what is the meaning of aid help decrease or method which is the correct of above three​

Answer 1

Answer:

Copper carbonate on heating dissociates to form two compounds , copper oxide and carbon dioxide . CuCO3 -----> CuO ( black )+ CO2 . On heating Copper carbonate , a black residue is formed and a gas is released which turns lime water milky . Thus , we can conclude that the gas evolved is carbon dioxide.