The compound that gives a pair of enantiomorphs is: (en = NH₂CH₂CH₂NH₂)

Enantiomorphs (or enantiomers) are mirror images that are non-superimposable, a property known as chirality or optical activity. This typically occurs in octahedral complexes involving didentate ligands.

1. Analysis of [Co(en)₂Cl₂]Cl: The complex ion is $[Co(en)_2Cl_2]^+$. This is an octahedral complex of the type $[M(AA)_2a_2]$, where 'AA' is the bidentate ligand ethylenediamine ($en$) and 'a' is the monodentate ligand chloride ($Cl^-$).

• It exhibits Geometrical Isomerism (cis and trans).
• The Trans-isomer has a plane of symmetry and is optically inactive (achiral).
• The Cis-isomer lacks a plane of symmetry and is chiral. Therefore, the cis-isomer exists as a pair of enantiomorphs (dextro and laevo forms) .

2. Other Options: $[Co(NH_3)_4Cl_2]NO_2$: Type $[Ma_4b_2]$. The cis-isomer is usually considered achiral in this context relative to the chelated complex, and the trans-isomer is definitely achiral. $[Cr(NH_3)_6][Co(CN)_6]$: Both ions are highly symmetrical octahedral species and do not show optical isomerism.

• $[Pt(NH_3)_4][PtCl_6]$: Contains a square planar cation and octahedral anion, neither of which supports enantiomerism in this form.

Therefore, $[Co(en)_2Cl_2]Cl$ is the compound that gives a pair of enantiomorphs.