Out of the following two coordination entities Which is chiral (optically active)
(a) `cis-[CrCI_(2)(OX)_(2)]^(3-)`
`trans -[CrCI_(2)(OX)_(2))]^(3-)` .

Explanation

The two geometrical isomers (a) and (b) are of the type `[M(AA)_(2)b_(2)]^(n+-)` , so (a) cis-isomer is chiral (optically active) The two entities are represented as

Trans form is optically inactive due to the presence of plane of symmetry as shown
.