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

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

$A$ blue colouration is not obtained when:

Write down the $IUPAC$ name for each of the following complexes and indicate the oxidation state,electronic configuration,and coordination number. Also,give the stereochemistry and magnetic moment of the complex:
$(i)$ $K[Cr(H_2O)_2(C_2O_4)_2] \cdot 3H_2O$
$(ii)$ $[Co(NH_3)_5Cl]Cl_2$
$(iii)$ $CrCl_3(py)_3$
$(iv)$ $Cs[FeCl_4]$
$(v)$ $K_4[Mn(CN)_6]$

Consider the following reaction and identify the correct statement:
$[M(gly)_2(NH_3)_2]^+ \xrightarrow[-2NH_3]{+gly} [M(gly)_3]$

When a metal rod $M$ is dipped into an aqueous colourless concentrated solution of compound $N$,the solution turns light blue. Addition of aqueous $NaCl$ to the blue solution gives a white precipitate $O$. Addition of aqueous $NH_3$ dissolves $O$ and gives an intense blue solution.
$1.$ The metal rod $M$ is
$(A)$ $Fe$ $(B)$ $Cu$ $(C)$ $Ni$ $(D)$ $Co$
$2.$ The compound $N$ is
$(A)$ $AgNO_3$ $(B)$ $Zn(NO_3)_2$
$(C)$ $Al(NO_3)_3$ $(D)$ $Pb(NO_3)_2$
$3.$ The final solution contains
$(A)$ $[Pb(NH_3)_4]^{2+}$ and $[CoCl_4]^{2-}$
$(B)$ $[Al(NH_3)_4]^{3+}$ and $[Cu(NH_3)_4]^{2+}$
$(C)$ $[Ag(NH_3)_2]^{+}$ and $[Cu(NH_3)_4]^{2+}$
$(D)$ $[Ag(NH_3)_2]^{+}$ and $[Ni(NH_3)_6]^{2+}$
Give the answer for questions $1$,$2$ and $3$.