For an octahedral complex, which of the following‘d’-electron configuration will give maximum CFSE

Low Spin electronic configuration corresponds to ${{\mathrm{t}}_{2\mathrm{g}}}^5{\mathrm{e}}_{\mathrm{g}}^0$
$\mathrm{CFSE}=\left[5\left(-0.4\times {\mathrm{\Delta }}_0\right)+0(0.6)\times {\mathrm{\Delta }}_0\right]=-0.2{\mathrm{\Delta }}_0$
Thus maximum value of CFSE will be for Low spin d⁵​electron configuration.