Which of the following complexes has a square planar geometry?

Which of the following is a square planar complex ion?

Which of the following complexes has a square planar geometry and $dsp^2$ hybridization?

Total number of $e^-$ in $e_g$ orbitals of $Mn$ for the complex $[MnO_4]^-$ is:

The incorrect statement about $Ni(CO)_4$ is

Reaction of $[Co(H_2O)_6]^{2+}$ with excess ammonia and in the presence of oxygen results into a diamagnetic product. Number of electrons present in $t_{2g}$-orbitals of the product is $.....$ .