Platinum ($\mathrm{II}$) forms square planar complexes and platinum ($\mathrm{IV}$) gives octahedral complexes. How many geometrical isomers are possible for the following complex? Describe their structures:

${\left[\mathrm{Pt}{\left({\mathrm{NH}}_3\right)}_4\mathrm{BrCl}\right]}^{2+}$

${\left[Pt\left({\mathrm{NH}}_3\right)\left({\mathrm{NO}}_2\right)Py\left({\mathrm{NH}}_2\mathrm{OH}\right)\right]}^{+}$ will form how many geometrical isomers?

Optical isomers are
(I) enantiomers
(II) non-superimposable
(III) have the property of chirality
(IV) form racemic mixture if present in $1:1$ ratio

Select the correct alternative.