Answer:
A. Na2SO4 + BaCl2 ----> BaSO4(solid, white) +2NaCl doublr replacement reaction
B. MnO2 + 4HCl ----> MnCl2 + 2H2O + Cl2 (gas) decomposition
C. CuSO4 + Fe ---> FeSO4 + Cu single replacement reaction
