Which of the following is a neutral ligand?

The number of coordinate bonds in $[Co(NH_3)_6]Cl_3$ is ...... .

Explain the following term with an example: Tetradentate ligands.

Potassium cyanide is made alkaline with $NaOH$ and boiled with thiosulphate ions. The solution is cooled and acidified with $HCl$ and this solution with iron $(III)$ chloride produces :-

Which of the following metal ions forms a complex with $CN^-$ having a coordination number of $2$?

Which one of the following is an ambidentate ligand?