(a) (i) The IUPAC name of $\left[\mathrm{Pt}{\left({\mathrm{NH}}_3\right)}_6\right]{\mathrm{Cl}}_4$ is Hexaammineplatinum (IV) chloride.
(ii) If , the electronic configuration of ${\mathit{d}}^4$ ion will be ${\mathit{t}}_{2\mathrm{g}}^3{\mathit{e}}_{\mathit{g}}^1$ as it is associated with weak field and high spin situation. Thus, the fourth electron will enter into ${\mathit{e}}_{\mathit{g}}$ orbital.
(iii) The complexes in which central atom or metal ion is surrounded by more than one type of ligands are called heteroleptic complexes. For example: ${\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_4{\mathrm{Cl}}_2\right]}^{+}$.
OR
(b) (i) (a)Pentaamminenitrito- $\mathrm{N}$-cobalt(III) is
${\left[\mathrm{Co}\left({\mathrm{NO}}_2\right){\left({\mathrm{NH}}_3\right)}_5\right]}^{2+}$
(b) Tetrahydroxidozincate(II) is ${\left[\mathrm{Zn}{\left(\mathrm{OH}\right)}_4\right]}^{-2}$
(ii) The difference of energy between the two sets of degenerated orbitals $({\mathit{t}}_{2\mathit{g}}.$ and ${\mathit{e}}_{\mathit{g}})$ after crystal field splitting is known as crystal field splitting energy. It is denoted by ${∆}_{\mathrm{o}}$.