Short Answer TypeHow would you account for the following?
(i) Transition metals exhibit variable oxidation states.
(ii) Zr (Z = 40) and Hf (Z = 72) have almost identical radii.
(iii) Transition metals and their compounds act as catalystName the two groups into which phenomenon of catalysis can be divided. Give an example of each group with the chemical equation involved.
Explain the following giving an appropriate reason in each case.
O2 and F2 both stabilise higher oxidation states of metals but O2 exceeds F2 in doing so.
Explain the following giving an appropriate reason in each case.
Structures of Xenon fluorides cannot be explained by Valence Bond approach.
How would you account for the following?
i) Many of the transition elements are known to form interstitial compounds.
ii)The metallic radii of the third (5d) series of transition metals are virtually the same as those of the corresponding group member of the second (4d) series.
iii) Lanthanoids from primarily +3 ions, while the actinoids usually have higher oxidation states in their compounds, +4 or even + 6 being typical.
Assign reasons for the following:
(i) Copper (I) ion is not known in aqueous solution.
(ii) Actinoids exhibit greater range of oxidation states than Lanthanoids.
Stability in the aqueous medium depends on the hydration energy of ions when they attract to water to water molecules. In aqueous solution, Cu+ ion undergoes oxidises and reduces simultaneously
in aqueous to give Cu and Cu2+ ion.
The relative stability of different oxidation states can be seen from their
Electrode potentials 
Due to more reduction electrode potential value of Cu+, it undergoes oxidation reaction quite feasible. Hence, the copper (I) ion is not known in aqueous solution.
(ii) The actinoids show a larger number of oxidation states because of the very small energy gap between the 5f, 6d and 7s subshells. The energies are decided on the basis of the (n+1) rule.
The (n+1) values of the three orbitals are under:
5f=5+3=8
6d=5+2=8
7s=7+ 1=8
All of the value comes to be same. Hence they have the same energy.
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