Facial-meridional isomers is associated with which one of the following complex (`M =`central metal) .

Fac-Mer isomerism is associated with which of the following types of complexes ? (M is the central metal. A-A is a symmetrical bidentate ligand. A,B,C & D are monodentate ligands)

Which one of the following complex ions has geometrical isomers ?

Which one of the following complex ions has geometrical isomers ?

Diethyl ether is not associated with which one of these isomers