Extraction of $Ag$ from sulphide ore and removal of unreacted silver from photographic plate involve complexes are respectively

The compound used in the treatment of lead poisoning is

The ligands in the anti-cancer drug $cis$-platin are:

The solution of $II A$ group precipitate in dilute $HNO_3$ when treated with $NH_4OH$ becomes blue because of the presence of

If a didentate ligand ethane-$1, 2$-diamine is progressively added in the molar ratio $en : Ni :: 1: 1, 2: 1, 3: 1$ to $[Ni(H_2O)_6]^{2+}$ aqueous solution,the following coordination entities are formed:
$I$. $[Ni(H_2O)_4en]^{2+}_{(aq)} -$ pale blue
$II$. $[Ni(H_2O)_2(en)_2]^{2+}_{(aq)} -$ blue/purple
$III$. $[Ni(en)_3]^{2+}_{(aq)} -$ violet
The wavelengths in $nm$ of light absorbed in the case of $I$ and $III$ are respectively:

Which of the following complexes is used as an anticancer agent?