[Ni (PPh_ 3 )_ 2 Cl_ 2 ] is a paramagnetic complex. Identify the...

In $[Ni(PPh_3)_2Cl_2]$, Nickel is in $+2$ oxidation state. $Ni^{2+}$ has a $3d^8$ electronic configuration.
The complex is given as paramagnetic. For a 4-coordinate $d^8$ system, paramagnetism implies a tetrahedral geometry ($sp^3$ hybridization) with two unpaired electrons.
Statement A: Tetrahedral complexes of the type $[MA_2B_2]$ do not exhibit geometrical isomerism because all positions are adjacent to each other. Thus, A is incorrect.
Statement B: Most $Ni(II)$ complexes are colored due to $d-d$ transitions. $[Ni(PPh_3)_2Cl_2]$ is a dark blue/green crystalline solid, not white. Thus, B is incorrect.
Statement C: With 2 unpaired electrons, the spin-only magnetic moment $\mu = \sqrt{n(n+2)} = \sqrt{2(2+2)} = \sqrt{8} \approx 2.83$ BM. Thus, C is correct.
Statement D: For a tetrahedral complex with $d^8$ configuration, the CFSE is calculated as $CFSE = [(-0.6 \times 4) + (0.4 \times 4)]\Delta_t = -0.8\Delta_t$. The statement mentions $-0.8\Delta_o$, which is incorrect as the complex is tetrahedral, not octahedral. Thus, D is incorrect.
Statement E: $Ni(CO)_4$ is a tetrahedral complex ($sp^3$ hybridization). Since $[Ni(PPh_3)_2Cl_2]$ is also tetrahedral, their geometrical arrangements are similar. Thus, E is correct.
The incorrect statements are A, B, and D.