Which of the following double salts does not exist?

The coordination number of cobalt in $[Co(en)_2Br_2]Cl_2$ is .........

Coordination number of $Fe$ in the complexes $[Fe(CN)_6]^{4-}$,$[Fe(CN)_6]^{3-}$ and $[FeCl_4]^{-}$ would be respectively

Three moles of $AgCl$ get precipitated when one mole of an octahedral coordination compound with empirical formula $CrCl_{3} \cdot 3NH_{3} \cdot 3H_{2}O$ reacts with excess of silver nitrate. The number of chloride ions satisfying the secondary valency of the metal ion is $......$

Primary and Secondary valency of $Co$ in the complex compound $[Co(en)_3]Cl_3$ is respectively . . . . . . .

Define the following terms: Homoleptic and heteroleptic complexes.