Number of ions present in $K_4[Fe(CN)_6]$

Which of the following is not considered a ligand?

Identify the total number of complexes having bidentate ligands in them from the following list of complexes:
$a$) Tetracyanonickelate$(II)$ ion
$b$) Trioxalatocobaltate$(III)$ ion
$c$) Sodium hexafluoroaluminate$(III)$
$d$) bis(ethylenediamine)dithiocyanatoplatinum$(IV)$

Identify the homoleptic complex from the following.

The number of ions produced when one molecule of $FeSO_4 \cdot (NH_4)_2SO_4 \cdot 6H_2O$ is dissolved in water is ...............

$1 \ mol$ of an octahedral metal complex with formula $MCl_{3} \cdot 2 \ L$ on reaction with excess of $AgNO_{3}$ gives $1 \ mol$ of $AgCl$. The denticity of ligand $L$ is ...... . (Integer answer)