Consider the coordination compound,$[Co(NH_3)_6]Cl_3$. In the formation of this complex,the species which acts as the Lewis acid is

The colour of $(NH_4)_2SO_4 \cdot Fe_2(SO_4)_3 \cdot 24H_2O$ is

In $[Ag(CN)_2]^-$,the number of $\pi$ bonds is

$A$ $1:3$ electrolyte in an aqueous solution is

Given below are two statements :
Statement $I :$ The identification of $Ni^{2+}$ is carried out by dimethyl glyoxime in the presence of $NH_{4}OH$.
Statement $II :$ The dimethyl glyoxime is a bidentate neutral ligand.
In the light of the above statements,choose the correct answer from the options given below:

In $K_4[Ni(C_2O_4)_3]$,what is the sum of the coordination number and the oxidation number of $Ni$?