0.4 mol [Co(NH3)5SO4]Br + 0.4 mol [Co(NH3)5Br]SO4 are present in 4 lit. solution.
2 lit. of mixture will contain 0.2 mol of each complex.
2 lit. mixture on reaction with excess AgNO3, 0.2 mole AgBr will be formed (Y).
2 lit. mixture on reaction with excess BaCl2, 0.2 mole BaSO4 will be formed (Z).