Mixture $X$ containing $0.02\;mol$ of $[C0(NH_3)_5 SO_4]Br$ and $0.02\;mol$ of $[C0(NH_3)_ Br]SO_4$ was prepared in $2$ litre of solution . $1$ litre of mixture X+ excess $AgNO_3\; \to\; Y$ $1$ litre of mixture $X+$ excess $Bacl_2 \; \to\; Z$. Number of moles of $Y$ and $Z$ are

$(a)\;0.01,0.01 \\ (b)\;0.02,0.01 \\(c)\;0.01,0.02\\(d)\;0.02,0.02$

Number of moles of $Br^{-}$ in the mixture $=0.02/2 \;mol$
$\qquad =0.01 \;mol/L$
$Br^{-}$ ions are produced in case of $[CO(NH_3)_5 Br]SO_4$ only
Now 1 litre of mixture +Excess $AgNO_3 \to Y$
$Br^{-} +Ag^{+} \to AgBr$
$y=0.01$
Also 1 litre of mixture +Excess $Bacl_2\; \to z$
$SO_4^{2+} +Ba^{2+} \to BasO_4$
$z=0.01$
Hence a is the correct answer.