In the complex $[Co(NH_3)_6]^{3+}$,which species act as a Lewis acid and a Lewis base,respectively?

Identify a ligand with a single donor atom from the following.

Identify the anionic ligand from the following.

Which of the following is not considered a ligand?

Assertion : $A$ chelating ligand must possess two or more lone pairs at such a distance that it may form suitable strain-free rings at the metal ion.
Reason : $H_2N-NH_2$ is a chelating ligand.

What is the coordination number of $Co$ in the complex $[CoF_6]^{3-}$?