The Crystal Field Stabilisation energy of (i) $[\text{CoF}_6]^{3-}$ and (ii) $[\text{Fe}(\text{H}_2\text{O})_6]^{3+}$ are ----- and ------- respectively.

For the complex $[\text{CoF}_6]^{3-}$:
The oxidation state of Co is $+3$. The electronic configuration of $\text{Co}^{3+}$ is $3d^6$.
Since $\text{F}^-$ is a weak field ligand, the complex is high-spin. The electrons are distributed in the $t_{2g}$ and $e_g$ orbitals as $t_{2g}^4 e_g^2$.
$\text{CFSE} = (-0.4 \times n_{t_{2g}} + 0.6 \times n_{e_g}) \Delta_0$
$\text{CFSE} = (-0.4 \times 4 + 0.6 \times 2) \Delta_0 = (-1.6 + 1.2) \Delta_0 = -0.4 \Delta_0$

For the complex $[\text{Fe}(\text{H}_2\text{O})_6]^{3+}$:
The oxidation state of Fe is $+3$. The electronic configuration of $\text{Fe}^{3+}$ is $3d^5$.
Since $\text{H}_2\text{O}$ is a weak field ligand, the complex is high-spin. The electrons are distributed as $t_{2g}^3 e_g^2$.
$\text{CFSE} = (-0.4 \times 3 + 0.6 \times 2) \Delta_0 = (-1.2 + 1.2) \Delta_0 = 0 \Delta_0$

Answer: (i) $-0.4\Delta_0$    (ii) $0\ \Delta_0$