Explain the following given appropriate reason:
i) Nickel does not form low spin octahedral complexes.
ii) The `pi`-complexes are known for the transition metals only.
iii) `Co^(2+)` is easily oxidised to `Co^(3+)` in the presence of a strong ligand.

Explain the following : (i) Low spin octahedral complexes of nickel are not known. (ii) The pi - complexes are known for transition elememts only. (iii) CO is a stroger ligand than NH_(3) for many metals.

Assign reason for each of the following : (i) Transition elements exhibit paramagnetic behaviour . (ii) Co^(2+) is easily oxidised in the presence of a strong ligand

(a) What is meant by the term lanthanoid contraction ? What is it due to and what consequences does it have on the chemistry of elements following lanthanoids in the periodic table ? (b) Explain the following observations : (i) Cu^(+) ion is unstable in aqueous solutions . (ii) Although Co^(2+) ion appears to be stable , it is easily oxidised to Co^(3+) ion in the presence of a strong ligand. (iii) The E_(Mn^(2+)//Mn)^(@) value for manganese is much more than expected from the trend for other elements in the series.

Spin only magnetic moment of an octahedral complex of Fe^(2+) in the presence of a strong field ligand in BM is:

From four transition metal octahedral complexes , (the choice given below) low spin electronic configuration arises only for

Give reasons for the following: (i) Transition metals form alloys. (ii) Mn_2O_3 is basic whereas Mn_2O_7 is acidic. (iii) Eu^(2+) is a strong reducing agent.