Which of the following statements about tetrahedral crystal fields are correct?

AThe $e$ set ( $d_{z^{2}}$ , $d_{x^{2} - y^{2}}$ ) lies lower in energy than the $t_{2}$ set ( $d_{x y}$ , $d_{yz}$ , $d_{z x}$ ).
B $Δ_{t} \approx 0.44 Δ_{o}$ for the same metal and ligands.
CThe $t_{2}$ orbitals point more nearly toward the ligands than the $e$ orbitals do.
DThe CFSE of high spin $[CoCl X_{4}] X^{2 -}$ is $- 0.8 Δ_{t}$ (pairing energy ignored).

Answer: A, B, C

In a tetrahedron the ligands lie between the axes, so the

t_{2}

orbitals (along the face diagonals) are closer to them and rise, while

e

falls;

Δ_{t} \approx \frac{4}{9} Δ_{o}

. For Co(II)

d^{7}

e^{4} t_{2}^{3}

gives

- 2.4 + 1.2 = - 1.2 Δ_{t}

, so statement 4 is false.