267.

In a geometry of [PtCl₄]^2– is square planar, what orbitals of platinum are involved in the bonding?

The electronic configuration of Platinum is [Xe] 4f¹⁴ 5d⁹ 6s¹ 

Or [Xe] 4f¹⁴ 5d⁸ 6s²

Oxidation of Pt in this complex is +2 thus, 



The four chlorine atom filled the empty orbital. Therefore the the hybridziation of [PtCl₄]^2– is dsp².

Complex should be tetrahedral instead of square planar theoretically. But the size of Pt is large that it forms strong bond with ligand. Due to which strong repulsion between the electron of Pt and ligand takes place which result in strong crystal field splitting. The strong field splitting breaks the degeneracy of d_x²_{- y}² and d_z² orbital. Hence stabilizes the square planer arrangement more than tetrahedral thus it should be square planar.