Using valence bond theory (VBT), account for the geometry, type of hybridization and magnetic property of `[NiCl_(4)]^(2-)`.

Explanation

The oxidation state of nickel inP `[NiCl_(4)]^(2+)` is+2. The outer electronic configuration of nickel(+2) is `3d^(8)4s^(0)`-

When weak ligand, Cl“ is approaching towards central metal ion, one 4s and three 4p orbitals hybridised to yield four `sp_(3)` hybrid orbitals pointing towards the four comers of tetrahedron
Each Cl- ion donates a pair of electrons to four `sp_(3)` hybrid orbitals to form tetrahedral complex. Due to the presence of two of unpaired electrons, the compound is paramagnetic in nature.
Conclusions:- 1/Hybridisation- `Sp_(3)`
2. Geometrical shape – tetrahedral
3. Magnetic property - Paramagnetic.