or
$\operatorname{trans}-\left[ Co \left( NH _{3}\right)_{4} Cl _{2}\right] C \ell$
As we know that ethylene diamine is a bidentate ligand and ammonia is a mono dentate ligand.
It means overall two ethylene diamine is required to replace the all neutral ligands (four ammonia) from the coordination sphere of this complex.
($en=$ ઇથિલીન ડાય એમાઈન)