Please assist with the following problem in Chemistry,

I heated 5g of CuCO3(OH)2*H20 in a flask and resulted in a black compound ( CuO? )whose weight was 3.327g giving a mass ratio of 1 to 0.6654.

a)Given that the molecular weight of CuCO3(OH)2 is 221.116g/mol while that of water is 18.015g/mol how can I show that the decomposed product is CuO not anhydrous copper carbonate hydroxide molecule CuCO3(OH)2?

b)For the unbalanced equation is; CuCO3(OH)2+heat ---> CuO + H2O correct?