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Give reasons for each of the following: ...

Give reasons for each of the following:
(i) Size of trivalent lanthanoid cation decrease with increase in the atomic number.
(ii) Transition metal fluorides are ionic in nature whereas bromides and chlorides are usualy covalent in nature.
(iii) Chemistry of all the lanthanoids is quite similar.

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The correct Answer is:
(i) Cause of lanthanide contraction.
(ii) As electronegativity of halogens decreases in the order `FgtClgtBr`, By , the ionic character of transition metal haldies decrease in the order `M-FgtM-ClgtM-Br`. Hence , fluorides are ionic whereas chloride and bromides are covalent.
(iii) The change in the size of the lanthanoids due to lanthanoid contraction is very small as we produceed from `La(Z=57)` to `Lu(Z=71)`. Hence , their chemical properties are similar . Moreover, their valence shell configuration remains the same because the electrons are added into the inner `4` f-subshell. hence , they show similar chemical properties .
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RESONANCE-D BLOCK ELEMENTS-EXERCISE-3 PART-III
  1. What is the basic difference between the electronic configuration of t...

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  2. Why do transition elements show variable oxidation state?

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  3. Give reasons for each of the following: (i) Size of trivalent lantha...

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  4. The E^(@) value in respect of the electrodes (Z=24), manganese (Z=25) ...

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  5. The outer electronic configuration of two members of the lanthanoid se...

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  6. Assign reason for each of the following statement: (i) The largest n...

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  7. Write all posible oxidation state of an element having atomic number 2...

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  8. Why is +2 oxidation state of mmanganese quite stable while the same is...

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  9. How is the variability in oxidation states fo transition metals differ...

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  10. Write the electronic configuration of the element with atomic number 1...

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  11. (a) Describe the general trends in the following properties of the fir...

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  12. How would you account for the fact that the transition metals and thei...

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  13. Assign reasons for the following : (i) The enthalpies of atomisatio...

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  14. How would you account for the fact that actinoids exhibit a larger num...

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  15. (a) Complete the following chemical reaction equation :(i)MnO(4(aq))^(...

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  16. Explain the following observation: (i) Generally there is an increas...

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  17. How would you account for the following? (i) The atomic radii of the...

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  18. Explain the following cases giving appropriate reason: (i) Nickel do...

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  19. (a) Complete the following chemical equation: (i) Cr(2)O(7)^(2-)(aq)...

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  20. How would you account for the following? (i) The atomic radii of the...

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