Assign reasons for the following : (i) The enthalpies of atomisation of transition elements are high. (ii) The transition metals and many of their compounds act as good catalyst. (iii) From element to element the actinoid contraction is greater than the lanthanoid contraction. (iv) The E^(@) value for the Mn^(3+)//Mn^(2+) couple is much more positive than that for Cr^(3+)//Cr^(2+) . (v) Scandium (Z = 21) does not exhibit variable oxidation states and yet it is regarded as transition element.

Transition metals, when they form interstitial compounds, the non-metals (H,B,C,N) are accommodated in:

Assign reasons for the following : (i) Transition metals and many fo their compounds act as good catalyst. (ii) Transition metals generally from coloured compounds.

Explain giving a suitable reason for each of the following : (i) Transition metals and their compounds are generally found to be good catalysts. (ii) Metal-metals bonding is more frequent for the 4d and the 5d series of transitions metals than that for the 3d series.

Explain the following observation : (i) Transition elements generally form coloured compounds. (ii) Zinc is not regaded as a transition element.

(a) Describe the general trends in the following properties of the first series of the transition elements: (i) Stability of +2 oxidation state (ii) Formation of oxometal ions (b) Assign reason for each of the following: (i) Transition elements exhibit variable oxidation states. (ii)Transition metal ions are usually coloured

Assertion Coordination compounds are generally formed by transition metals Reason Transition metals generally have partly filled d-orbitals of the nth shell .

Assign reasons for each of the following : (i) Transiti9n metals generally form coloured compounds. (ii) Manganese exhibits the highest oxidation state of+ 7 among the 3d series of transition elements.

Explain the following (a) Zr and Hf exhibit similar properties. (b) Most of the transition elements show large number of oxidation states.

Colour of compounds occurs due to phenomenon of polarisation, charge transfer, d-d transition and H.O.M.O.L.U.M.O transition. Most of the transition metal transition metal complex compound are coloured either due to d-d electrons transition or charge transfer and ionic compounds are coloured due to polarisation of anion. Q. Which of the following is correct about KFe^(II)[underset(III)(Fe)(CN_(6))] and KFe^(III)[underset(II)(Fe)(CN_(6))] complex compounds?