Which of the following outer orbital complexes has the maximum number of unpaired electrons?

Explain why $[Co(NH_{3})_{6}]^{3+}$ is an inner orbital complex whereas $[Ni(NH_{3})_{6}]^{2+}$ is an outer orbital complex.

In which of the following complex ions is the value of the magnetic moment (spin only) $\sqrt{3} \ BM$ and outer $d$-orbitals are used in hybridization?

$[Ni(PPh_3)_2Cl_2]$ is a paramagnetic complex. Identify the $INCORRECT$ statements about this complex.
$A$. The complex exhibits geometrical isomerism.
$B$. The complex is white in colour.
$C$. The calculated spin-only magnetic moment of the complex is $2.84 \ BM$.
$D$. The calculated $CFSE$ (Crystal Field Stabilization Energy) of $Ni$ in this complex is $-0.8 \Delta_0$.
$E$. The geometrical arrangement of ligands in this complex is similar to that in $Ni(CO)_4$.
Choose the correct answer from the options given below:

The number of unpaired electrons in $Ni(CO)_4$ is

The structure of which of the following chloro species can be explained on the basis of $dsp^2$ hybridization?