Which type of atomic orbitals hybridize to form a square planar complex?

When $Ag^{+}$ reacts with excess of sodium thiosulphate,the obtained species having charge and geometry respectively will be?

Match the following:

Column-$I$ Complex	Column-$II$ Structure / Geometry / Property
$A$. $[Ni(CN)_4]^{2-}$	$I$. Tetrahedral / Paramagnetic
$B$. $[Ni(CO)_4]$	$II$. Tetrahedral / Diamagnetic
$C$. $[NiCl_4]^{2-}$	$III$. Square planar / Diamagnetic

The correct match is:

If $Ni^{2+}$ is replaced by $Pt^{2+}$ in the complex $[NiCl_2Br_2]^{2-}$,which of the following properties are expected to change?
$A.$ Geometry
$B.$ Geometrical isomerism
$C.$ Optical isomerism
$D.$ Magnetic properties

In which of the following configurations will there be the possibility of both paramagnetism and diamagnetism,depending on the nature of the ligands?

The complex ion $[Cu(NH_3)_4]^{2+}$ is: