Sulphide ions react with sodium nitroprusside in a basic medium giving a coloured solution. In the reaction,the oxidation state of iron:

The sum of the total number of $Cr-O$ bonds in chromate $(CrO_4^{2-})$ and dichromate $(Cr_2O_7^{2-})$ ions is:

$A$ mixture $X$ containing $0.02 \, mol$ of $[Co(NH_3)_5SO_4]Br$ and $0.02 \, mol$ of $[Co(NH_3)_5Br]SO_4$ is dissolved in water to make a $2 \, L$ solution.
$1 \, L \, of \, X + \text{Excess of } AgNO_3 \rightarrow Y \, mol \, of \, ppt.$
$1 \, L \, of \, X + \text{Excess of } BaCl_2 \rightarrow Z \, mol \, of \, ppt.$
Then $Y$ and $Z$ are respectively ...............

Given below are two statements:
Statement $I$ : Dimethyl glyoxime forms a six-membered covalent chelate when treated with $NiCl_2$ solution in presence of $NH_4OH$.
Statement $II$ : Prussian blue precipitate contains iron both in $(+2)$ and $(+3)$ oxidation states.
In the light of the above statements,choose the most appropriate answer from the options given below:

Select the correct statement$(s)$ regarding the $[Ni(DMG)_2]$ complex compound.

The volume (in $mL$) of $0.1 \ M$ $AgNO_3$ required for complete precipitation of chloride ions present in $30 \ mL$ of $0.01 \ M$ solution of $[Cr(H_2O)_5Cl]Cl_2$, as silver chloride is close to