$\mathop {[Co\,{{(N{H_3})}_5}B{r_2}]S{O_4}}\limits_{0.02\,{\text{mole}}} + BaC{l_2} \to $$\mathop {[Co\,{{(N{H_3})}_5}Br]\,C{l_2}}\limits_{0.02\,{\text{mole}}\,(z)} + BaS{O_4}$
On using one lit. solution, we will get $ 0.01$ $mole$ $y $ and $0.01$ $mole$ $z.$