Which among the following is $NOT$ a neutral ligand?

Given below are two statements :
Statement $I$ : $[Co(NH_3)_6]^{3+}$ is a homoleptic complex whereas $[Co(NH_3)_4 Cl_2]^{+}$ is a heteroleptic complex.
Statement $II$ : Complex $[Co(NH_3)_6]^{3+}$ has only one kind of ligands but $[Co(NH_3)_4 Cl_2]^{+}$ has more than one kind of ligands.
In the light of the above statements,choose the correct answer from the options given below.

Identify the cationic complex from the following.

On the basis of the following observations made with aqueous solutions,assign secondary valences to metals in the following compounds:

Formula	Moles of $AgCl$ precipitated per mole of the compound with excess $AgNO_3$
$(i) PdCl_2 \cdot 4NH_3$	$2$
$(ii) NiCl_2 \cdot 6H_2O$	$2$
$(iii) PtCl_4 \cdot 2HCl$	$0$
$(iv) CoCl_3 \cdot 4NH_3$	$1$
$(v) PtCl_2 \cdot 2NH_3$	$0$

The molecular formula of tris(ethylenediamine)cobalt$(III)$ sulfate is:

State the limitations of Werner's coordination theory.