Consider an octahedral complex Ma₂b₂cd, where a, b, c, and d are monodentate ligands. The number of enantiomeric pairs for the complex is

Concept:-

Stereoisomerism in coordination compounds:

There are two types of isomerism found in coordination compounds

• Geometrical isomerism: Also called cis/trans isomerism
• Optical isomerism: compounds having the same molecular and structural formula but differ in the direction of rotation of plane-polarized light and the compounds are called optically active compounds

Explanation:

• In octahedral complexes, both types of isomerism is found depending upon their structure.  
• Enantiomers are the optically active compounds that are mirror image to each other but are not superimposable and there is no plane of symmetry present in enantiomers.
• Only cis isomers are optically active because there is no plane of symmetry present in cis isomers.
• Ma₂b₂cd has eight isomers, including two pairs of enantiomers
• In the given example Ma₂b₂cd, there are two pair of enantiomers present as shown below:

In the given image there are two cis isomers that will have their non-superimposable mirror image, therefore, each cis isomers d and l form of isomers which are optically active. Hence there are two pairs of enantiomers are present.

Conclusion:

Hence the correct answer is two.