Which of the following is not a double salt but a coordination compound?

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.

The number of ions produced when cuprammonium sulfate is dissolved in water is $......$.

In which of the following compounds,the transition metal is in an oxidation state of zero?

Which of the following is not a chelating ligand?

Which of the following complexes gives only one mole of $AgCl$ when reacted with excess $AgNO_3$?