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

$0.001 \ mol$ of $Co(NH_3)_5(NO_3)(SO_4)$ was passed through a cation exchanger. The acid coming out of it required $20 \ mL$ of $0.1 \ M$ $NaOH$ for neutralization. Hence,the complex is:

Match each coordination compound in List-$I$ with an appropriate pair of characteristics from List-$II$ and select the correct answer using the code given below the lists. $\{en = H_2NCH_2CH_2NH_2\}$,atomic numbers:$\{Ti = 22; Cr = 24; Co = 27; Pt = 78\}$

List-$I$	List-$II$
$P$. $[Cr(NH_3)_4Cl_2]Cl$	$1$. Paramagnetic and exhibits ionisation isomerism
$Q$. $[Ti(H_2O)_5Cl](NO_3)_2$	$2$. Diamagnetic and exhibits cis-trans isomerism
$R$. $[Pt(en)(NH_3)Cl]NO_3$	$3$. Paramagnetic and exhibits cis-trans isomerism
$S$. $[Co(NH_3)_4(NO_3)_2]NO_3$	$4$. Diamagnetic and exhibits ionisation isomerism

Give the oxidation state,$d$-orbital occupation,and coordination number of the central metal ion in the following complexes:
$(i)$ $K_{3}[Co(C_{2}O_{4})_{3}]$
$(ii)$ $cis-[Cr(en)_{2}Cl_{2}]Cl$
$(iii)$ $(NH_{4})_{2}[CoF_{4}]$
$(iv)$ $[Mn(H_{2}O)_{6}]SO_{4}$

$[Ni(CO)_4]$ is diamagnetic. Which of the following statements is correct for this complex?

Some statements are given below $-$
$(a)$ Coordination compounds $[Pt(NH_3)_3(NCS)]$ and $[Pt(NH_3)_3(SCN)]$ are examples of linkage isomerism.
$(b)$ In the coordination compound $K_4[Ni(CN)_4]$, the oxidation state of nickel is zero.
$(c)$ The hybridization, shape and magnetic moment of $K_3[Cu(CN)_4]$ are respectively $dsp^2$, square planar, $1.73 \ B.M.$
$(d)$ $[Cr(NCS)(NH_3)_5][ZnCl_4]$ exhibits only linkage isomerism.