The number of geometrical isomers possible in triamminetrinitrocobalt $\left(\mathrm{III}\right)$ is $\mathrm{X}$ and in trioxalatochromate $\left(\mathrm{III}\right)$ is $\mathrm{Y}.$ Then the value of $\mathrm{X}+\mathrm{Y}$ is $\_\_\_\_.$

The number of stereo isomers possible for ${\left[\mathrm{Co}{\left(\mathrm{ox}\right)}_2\left(\mathrm{Br}\right)\left({\mathrm{NH}}_3\right)\right]}^{2-}$ is __________.

[$\mathrm{ox}=$ oxalate]

Arrange the following Cobalt complexes in the order of increasing Crystal Field Stabilization Energy (CFSE) value.

Complexes: $\begin{array}{cccc}\underset{\mathrm{A}}{{\left[{\mathrm{CoF}}_6\right]}^{3-}},& \underset{\mathrm{B}}{{\left[\mathrm{Co}{\left({\mathrm{H}}_2\mathrm{O}\right)}_6\right]}^{2+}},& \underset{\mathrm{C}}{{\left[\mathrm{Co}{\left({\mathrm{NH}}_3\right)}_6\right]}^{3+}}\text{ and }\underset{\mathrm{D}}{{\left[\mathrm{Co}(\mathrm{en}{)}_3\right]}^{3+}}& \end{array}$

Choose the correct option :