Which complexes have zero oxidation state?

According to the Lewis theory,a ligand is .......

Which among the following coordination compounds does not have a coordination number equal to the number of ligands?

One mole of the octahedral complex compound $Co(NH_3)_5Cl_3$ gives $3$ moles of ions on dissolution in water. One mole of the same complex reacts with excess of $AgNO_3$ solution to yield two moles of $AgCl_{(s)}$. The structure of the complex is :

Which one is a Homoleptic complex?

Identify the monodentate ligand from the following.