Which of the following complexes will show the largest splitting of $d$-orbitals?

Which one of the following complexes has the highest magnitude of crystal field splitting energy $\left(\Delta_0\right)$?

The transition metal complex with the highest value of crystal field splitting $(\Delta_{0})$ is ........ .

The $\Delta_0$ of a coordination complex of a metal ion $(3d^1)$ is $1000 \ kJ \ mol^{-1}$. If the energy of $t_{2g}$ orbitals is $-400 \ kJ \ mol^{-1}$,the energy (in $kJ \ mol^{-1}$) of $e_g$ orbitals is

Arrange the following complex ions in increasing order of crystal field splitting energy $(\Delta_{0}):$ $[Cr(Cl)_{6}]^{3-}, [Cr(CN)_{6}]^{3-}, [Cr(NH_{3})_{6}]^{3+}$

The $CFSE$ for $[CoCl_6]^{4-}$ complex is $18000 \ cm^{-1}$. The $\Delta_t$ for $[CoCl_4]^{2-}$ will be ........... $cm^{-1}$.