D Block Elements

The valence shell electronic configuration of Ni is :

Zinc coated with copper is used as a reducing agent.

Fe is a basic oxide, neutralised by HCI spontaneously forming FeCI and water.

undergo d-d transition, exhibit colour.

Ammonium dichromate [(NH ]on heating decomposes producing green powder of Cr and N (g) is evolved

The structure of dichromate ion is :
Exhibit resonance phenomena. Except the bridged Cr- O-Cr all Cr-O bonds are equivalent.

In Cr , Cr is in + 6 oxidation state because Cl is in ( - 1) and oxygen is in (-2) oxidation states

Ammonium dichromate on heating produces also gives N on heating :

Oxidation number Mn in is 7 and in

KMn is itself a very strong oxidising agent, cannot oxidise it

In CuCl , Cu has - configuration, exhibit d-d transition and show colour. Similarly in VOCl configuration, car exhibit d-d transition and show colour.

A water soluble complex with silver and dilute aqueous solution of NaCN is In the cyanide process, the native silver is crushed and treated with aqueous NaCN solution and aerated.

(stable)
So, act as a reducing agent

(stable)
So, act as a oxidising agent

(A) and both gives green colour in flame test and cannot distinguished.
(B) belongs to group-II of cationic radical will gives ppt. of CuS in acidic medium.
(C) Cu+2 and Mn+2 both form ppt. in basic medium.
(D)

\underset{\text{}}{{2MnO2}} \underset{\text{(W)}}{{2K2MnO4 + 2H2O}}
Electrolysis of aq oxidises to
\underset{\text{(W)}}{{K2MnO4}} \underset{\text{(X)}}{{2K2MnO4 + 2KOH + H2}}
in acidic medium undergoes disproportionation
\underset{\text{(Y)}}{{3MnO^{2-}_{4}}} \underset{\text{(Z)}}{{2MnO^{-}_{4} + MnO2 + 2H2O}}
is green in colour and is in purple colour. Both are tetrahedral in shape involving p - d bond.