With the help of Valence Bond theory account for hybridisation, geometry and magnetic property of `[Ni(CN)_(4)]^(2-)` complex ion `[Z" for "Ni=28]`

Explanation

In the complex `[Ni(CN)_(4)]^(2-)`, nickel is in +2 Oxidatioin state and is `d^(8)` ion.
The hybridisation scheme is like this,
Ni :
The Strong ligand like `CN^(-)` pairs up the unpaired electrons iin 3d-orbital
`:.` Ni :
The empty `dsp^(2)` hybridised orbitals overlap with the filled orbitals, one from each of the `CN^(-)` ligand.
Ni :
The complex is square planar, and is diamagnetic because all the electrons are paired up in the complex.