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How do you account for the following: ...

How do you account for the following:
(i) all scandium salts are white ?
(ii) the first ionisation enthalpies of 5d transition elements are higher than those of the 3d and 4d transition elements in respective groups ?

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(i) In scandium salts, scandium has +3 oxidation state, `Sc^(3+)` does not have unpaired electrons and therefore there is no d-d transition. Hence its salts are white.
(ii) Due to poor shielding effect of 5d and 4f- electrons, the effective nuclear charge increases. Hence ionisation enthalpy of 5d transition elements is more than that of 3d and 4d-elements in respective groups.
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U-LIKE SERIES-THE D-AND F-BLOCK ELEMENTS -SHORT ANSWER QUESTIONS (2 marks each)
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  2. Explain why (i) E^(@) for Mn^(3+)//Mn^(2+) couple is more positive t...

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  3. With the help of ionic equations, describe what happens when (i) pH ...

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  4. Although Zr belongs to 4d and Hf belongs to 5d transition series, but ...

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  5. The outer electronic configurations of two transition metals are (i) 3...

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  6. The second and third rows of transition elements resemble each other m...

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  7. Although Cr^(3+) and Co^(2+) ions have the same number of unpaired ele...

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  8. Although +3 oxidation state is the characteristic oxidation state of l...

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  9. When orange solution containing CrO(7)^(2-) ion is treated with an alk...

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  10. Explain why does the colour of KMnO(4) disappear when oxalic acid is a...

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  11. E^(@) of Cu is + 0.34 V while that of Zn is – 0.76 V. Explain.

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  12. The halides of transition elements become more covalent with increasin...

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  13. Reactivity of transition elements decreases almost regularly from Sc t...

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  14. Explain any one of the following statements : (i) The transition met...

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  15. Answer the following questions : (i) Which element in the first seri...

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  16. How do you account for the following: (i) all scandium salts are whi...

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  17. Why is the +2 oxidation state of manganese quite stable, while the sam...

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  18. While filling up of the electrons in the atomic orbitals, the 4s orbit...

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  20. Identify the following : (i) Oxoanion of chromium which is stable in...

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