The number of stereo isomers possible for Co ox 2 Br NH 3 2 - is __________. [ ox = oxalate]

Total number of stereoisomers in ${\left[\mathrm{Co}{\left(\mathrm{ox}\right)}_2\mathrm{Br}\left({\mathrm{NH}}_3\right)\right]}^{2\mathrm{\Theta }}$ i.e. $\simeq {\left[\mathrm{M}{\left(\mathrm{AA}\right)}_2\mathrm{ab}\right]}^{2-}$

$\to$ cis is optically active isomers and trans is optically inactive isomer

$\to$ Hence total isomers is $=3$