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A solution of [Ni(H(2)O)(6)]^(2+) is gre...

A solution of `[Ni(H_(2)O)_(6)]^(2+)` is green but a solution of `[Ni(CN)_(4)]^(2-)` is colourless. Why?

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`rarr` In the complex `[Ni(H_(2)O)_(6)] ^(2+), H_(2)O` molecules are weak ligands they do not cause pairing. So the complex has two unpaired electrons. d-d-transitions takes place due to absorption of red light radiation and emission of green colour occurs.
`rarr` In the complex `[Ni(CN)_(4)]^(2-), CN^(-)` ions are strong ligands they cause pairing. So there is no unpaired electrons so, no d-d transition. Hence it is colourless.
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VIKRAM PUBLICATION ( ANDHRA PUBLICATION)-D AND F- BLOCK ELEMENTS AND CO-ORDINATION COMPOUNDS -VERY SHORT ANSWER QUESTIONS
  1. What is difference between a double salt and complex compound ?

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  2. What is a ligand ?

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  3. Give one example each for ionic and neutral ligands.

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  4. How many moles of AgCl is precipitated when I mole of CoCl(3) is treat...

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  5. What is a chelate ligand ? Give example.

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  6. What is an ambidentatc ligand ? Give example.

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  7. CuSO(4).5H(2)O is blue in colour where as anhydrous CuSO(4) is colourl...

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  8. FeSO(4) solution mixed with (NH(4))(2)SO(4) solution in 1 : 1 molar ra...

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  9. How many geometrical isomers are possible in the following coordinatio...

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  10. How many geometrical isomers are possible in the following coordinatio...

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  11. What is the coordination entity formed when excess of aqueous KCN is a...

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  12. [Cr(NH(3))(6)]^(3+) is paramagnetic while [Ni(CN)(4))]^(2-) is diamagn...

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  13. A solution of [Ni(H(2)O)(6)]^(2+) is green but a solution of [Ni(CN)(4...

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  14. [Fe(CN)(4)]^(2-) and [Fe(H(2)O)(6)]^(2+) are of different colours in d...

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  15. What is the oxidation state of cobalt in K[Co(CO)(4)]

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  16. What is the oxidation state of cobalt in [Co(NH(3))(6)]^(3+) ?

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  17. Give the formula the follow complexes. Potassium hexacyano ferrate (II...

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  18. Write the formulas for the follow co-ordination compounds Tetracarbo...

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  19. What are interstitial compounds ?

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  20. Cu^(+2) forms halides like CuF(2), CuCl(2) and CuBr(2) but not CuI(2)....

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