$0.4$ mol of $Z$ is formed
Step 1: Understanding the complexes.
$[\mathrm{Co(NH_3)_5SO_4}]Br$ gives Br$^-$ as counter ion in solution.
$[\mathrm{Co(NH_3)_5Br}]SO_4$ gives SO$_4^{2-$} as counter ion in solution.
Step 2: Calculating moles in 2 L solution.
Total volume = $4$ L
So, $2$ L contains half the moles.
\[ \text{Moles of each salt in 2 L} = \frac{0.4}{2} = 0.2 \] Step 3: Reaction with AgNO$_3$.
Only free Br$^-$ reacts with $\mathrm{AgNO_3}$ to form $\mathrm{AgBr}$.
Moles of $\mathrm{AgBr}$ formed:
\[ 0.2\,\text{mol} \] Step 4: Reaction with BaCl$_2$.
Only free SO$_4^{2-}$ reacts with $\mathrm{BaCl_2}$ to form $\mathrm{BaSO_4}$.
Moles of $\mathrm{BaSO_4}$ formed:
\[ 0.2\,\text{mol} \] Step 5: Final conclusion.
The correct statement is that $0.2$ mol of $Z$ is formed.
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)

Cobalt chloride when dissolved in water forms pink colored complex $X$ which has octahedral geometry. This solution on treating with cone $HCl$ forms deep blue complex, $\underline{Y}$ which has a $\underline{Z}$ geometry $X, Y$ and $Z$, respectively, are
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)