The oxidation state of $Mo$ in its oxo-complex species $[Mo_2O_4(H_2O)_2(C_2H_4)_2]^{2-}$ is :

Provide the $\text{IUPAC}$ names for the following coordination compounds:
$(i)$ ${K_2}[Zn(Cl)_4]$
$(ii)$ ${K_4}[Fe(CN)_6]$
$(iii)$ $[Co(NH_3)_4Cl_2]Cl$
$(iv)$ $[Fe(NH_3)_6]^{3+}$

State the $IUPAC$ name of the following complex: $[Fe(NH_3)_6][Fe(CN)_6]$

$K_3[Fe(CN)_6]$ is called

The $IUPAC$ name of the compound $(NH_4)_2[Ni(C_2O_4)_2(H_2O)_2]$ is

Which of the following formulae represents the trioxalatocobaltate$(III)$ ion?