Explain in detail the meso- form of an optical compound.

Meso form is the stereoisomer of any compound (having more than one chiral carbons) in which the entire molecule contains chiral carbons (stereogenic centers ) but due to presece of symmetry in the molecule the molecule loses its chirality.

It is optically inactive due to internal compensation (the rotation caused in plane of polarised light by one half is cancelled by the rotation caused due an another half of the molecule).

Because every molecule of the meso compound  is optically inactive so it cant be separated in two optically active compounds (as in the case of racemic mixture) by any method.

Meso compounds donot exist as any pair of enantiomers as their mirror image is overlapping.