Which from following coordinate complexes is a heteroleptic complex?

Which from the following statements about $\left[\mathrm{Co}\left(\mathrm{NH}_3\right)_6\right]^{3+}$ complex is NOT correct?

Which from following ligands is able to form linkage isomers?

Identify the total number of complexes having bidentate ligands in them from following list of complexes.

a) Tetracyanonickelate(II) ion

b) Trioxalatocobaltate(III) ion

c) Sodium hexafluoroaluminate(III)

d) bis(ethylenediamine)dithiocyanatoplatinum(IV)