In which case racemic mixture is obtained on mixing its mirror images in `1:1` molar ratio?

Options

A. (a) `[Cr(en)_3]^(3+)`
B. (b) `[Ni(DMG)_2]`
C. (c) `cis-[Cu(Gly)_2]`
D. (d) All of these

Answer

A

Explanation

(a) `[Cr(en)_3]^(3+)` exists in d- and l-forms due to the absence of one of the symmetry element(s). So it will give racemic mixture when d-and l-forms are mixed in `1:1` molar ratio.
(b) `[Ni(DMG)_2]` has square planar geometry and thus has mirror plane so optically inactive.
(c) cis`-[Cu(Gly)_2]` has square planar geometry and thus have mirror plane so optically inactive.