When crystals of `CuSO_(4)` are dissolved in water, there is hardly any evidence for the presence of `Cu^(2+)` ions or ammonia molecules. A new ion `[Cu(NH_(3))_(4)]^(2+)` is furnished in which ammonia molecules are directly linked with the metal ion . Similarly the aqueous solution of `Fe(CN)_(2).4KCN` does not give tests of `Fe^(2+)` and `CN^(-)` ions but gives test of a new ion, `[Fe(CN)_(6)]^(4-)` also called complex ions.
Predict the incorrect statements from the options given below :

Options

A. `[Ni(CN)_(6)]^(3-)` is weakly paramagnetic while `[Fe(CN)_(6)]^(4-)` is diamagnetic
B. `[Ni(CO)_(4)]` possesses tetrahedral geometry while `[Ni(CN)_(4)]^(2-)` is square planar
C. `[Ni(CN)_(4)]^(2-)` is diamagnetic while `[NiCl_(4)]^(2-)` is paramagnetic
D. `[Cu(en)_(2)]^(2+)` is less stable than `[Cu(NH_(3))_(4)]^(2+)`

Answer

d

Explanation

`[Cu(en)_2]^(2+)` is more stable than `[Cu(NH_3)_4]^(2+)` as it is involved in the formation of chelate.