Four separate test tubes contain aqueous solutions of different metal salts. To each test tube, a few drops of aqueous sodium carbonate, Na2CO3(aq)\text{Na}_2\text{CO}_3\text{(aq)}Na2CO3(aq), are added.
Which of the following mixtures will yield both a brown precipitate and bubbles of a gas?
FeSO4(aq)\text{FeSO}_4\text{(aq)}FeSO4(aq) and Na2CO3(aq)\text{Na}_2\text{CO}_3\text{(aq)}Na2CO3(aq)
Fe(NO3)3(aq)\text{Fe(NO}_3)_3\text{(aq)}Fe(NO3)3(aq) and Na2CO3(aq)\text{Na}_2\text{CO}_3\text{(aq)}Na2CO3(aq)
CuSO4(aq)\text{CuSO}_4\text{(aq)}CuSO4(aq) and Na2CO3(aq)\text{Na}_2\text{CO}_3\text{(aq)}Na2CO3(aq)
Al2(SO4)3(aq)\text{Al}_2(\text{SO}_4)_3\text{(aq)}Al2(SO4)3(aq) and Na2CO3(aq)\text{Na}_2\text{CO}_3\text{(aq)}Na2CO3(aq)
