How will you account for the following :
(i) Cobalt (II) is stable in aqueous solution but in the presence of a complexing agent, it is easily oxidized.
(ii) Out of `d^(4)` species, `Cr^(2+)` is strongly reducing while `Mn^(2+)` is strongly oxidising .

Cobalt (II) is stable in aqueous solution but in the presence of complexing reagents ( strong field ligands ) it is readily oxidised. Why ?

(a) How would you account for the following : (i) Cobalt (II) is stable in aqueous solution but in the presence of strong ligands, it is easily oxidised. (ii) The transition metals form interstitial compounds. (iii) Silver halides find use in photography. (b) What is lanthanoid contraction ? Mention its main consequences.

How would you account for the following: of the d^(4) species Cr^(2+) is strongly reducing while manganese(III) is strongly oxiding. Cobalt(II) is stable in aqueous solution but in the presence of complexing reagents it is easily oxidised. The D^(1) configuration is very unstable in ions.

Account for the following (i) Co(II) is stable in aqueous solution but in the presence of strong ligand and air , it can get oxidized to Co(II) . (ii) [Ni(CN)_(4)]^(2-) is square planar and diamagnetic whereas [NiCl_(4)]^(2-) is tetrahedral and paramagnetic .