The yellow compound $PbCrO_4$ dissolves upon treatment with a hot $NaOH$ solution. The lead-containing product formed is a:

$5.33 \text{ g}$ of $CrCl_3 \cdot 6H_2O$, which is a $1:3$ electrolyte, is dissolved in water and passed through a cation exchanger. The chloride ions in the eluted solution, on treatment with $AgNO_3$, result in $8.61 \text{ g}$ of $AgCl$. The ratio of moles of complex reacted and moles of $AgCl$ formed is . . . . . . $\times 10^{-2}$. (Nearest integer) [Molar mass in $\text{g mol}^{-1}$: $Cr = 52, Ag = 108, Cl = 35.5, H = 1, O = 16$]

Which of the following complexes is the most stable: $[Fe(H_2O)_6]^{3+}$,$[Fe(CN)_6]^{3-}$,$[Fe(C_2O_4)_3]^{3-}$,or $[FeCl_6]^{3-}$?

Cobalt$(III)$ chloride forms a green coloured complex '$X$' with $NH_3$. The number of moles of $AgCl$ formed when an excess of $AgNO_3$ solution is added to $100 \ mL$ of a $1 \ M$ solution of '$X$' is:

$AgNO_3 \xrightarrow{\Delta} (W) + (X) + O_2$
$(X) + H_2O \longrightarrow HNO_2 + HNO_3$
$(W) + HNO_3 \longrightarrow Y + NO + H_2O$
$(Y) + Na_2S_2O_3(\text{excess}) \longrightarrow (Z) + NaNO_3$
Identify $(W)$ to $(Z)$.

Which of the following is a strong field ligand?