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State reasons for the following: (i) C...

State reasons for the following:
(i) Cu (1) ion is not stable in an aqueous solution.
(ii) Unlike `Cr^(3+), Mn^(2+), Fe^(3+)` and the subsequent other `M^(2+)` ions of the 3d series of elements, the 4d and 5d series metals generally do not form stable cationic species.

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(i) Cu (I) ion does not exhibit sufficiently negative value of enthalpy of hydration and it proportionates into 0 and +2 oxidation states of Cu.
`2Cu^(+)toCu^(2+)+Cu`
(ii) 4d and 5d series transition metals have greater enthalpies of atomisation. Thus, there are strong metal-metal interactions between them. This is the reason why they do not form stable cationic species.
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U-LIKE SERIES-THE D-AND F-BLOCK ELEMENTS -SHORT ANSWER QUESTIONS (2 marks each)
  1. What are transition elements ? Write two characteristics of the transi...

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  2. Why do transition elements show variable oxidation states ? In 3d seri...

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  3. State reasons for the following: (i) Cu (1) ion is not stable in an ...

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  4. Complete the following chemical equations : (i) Cr(2)O(7)^(2-)+H^(+)...

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  5. Complete the following chemical equations : (i) MnO(4)^(-)(aq)+S(2)O...

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  6. Assign reasons for the following: (i) Copper(I) ion is not known in ...

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  7. How would you account for the following: (i) Cr^(2+) is reducing in ...

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  8. Explain the following observations: (i) Generally there is an increa...

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  9. Complete the following chemical reaction equations : (i) MnO(4)^(-)(...

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  10. Explain the following giving reasons : (i) It is difficult to separa...

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  11. The sum of the first and second ionisation enthalpies and those of thi...

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  12. Compare the relative stability of +2 oxidation states in aqueous solut...

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  13. A mixed oxide of iron and chromium FeO.Cr(2)O(3) is fused with sodium ...

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  14. Complete the following reactions : (a) (NH(4))(2)Cr(2)O(7)overset(He...

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  15. Why E^(@) values for Mn, Ni and Zn are more negative than expected ?

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  16. Out of Cu(2)Cl(2) and CuCl(2), which is more stable and why ?

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  17. Although fluorine is more electronegative than oxygen, but the ability...

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  18. Transition metals show high melting points. Why?

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  19. When Cu^(2+) is treated with KI, a white precipitate is formed. Explai...

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  20. When a brown compound of manganese (A) is treated with HCl it gives a ...

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