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The D-And-f-Block Elements

Question
CBSEENCH12011276
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Which of the following ions will exhibit colour in aqueous solutions?

  • La3+ (Z = 57)

  • Ti3+ (Z = 22)

  • Lu3+

  • Sc3+

Solution

B.

Ti3+ (Z = 22)

Colour is obtained as a consequence of d-d (or f-f) transition, the presence of unpaired electrons is necessary conditions.
La3+ (Z = 57) = [Xe] 4f0 5d0 6s0 [ no unpaired electron]
Ti3+ (Z = 22) = [Ar] 3d1 4s0  [one unpaired electron]
Lu3+ (Z = 71) = [Xe] 4f14 5d0 6s0 [no unpaired electron]
Sc3+(Z = 21) = [Ar] 3d0 4s0 [no unpaired electron]
Hence, only Ti3+ will exhibit colour in aqueous solution.

Some More Questions From The d-And-f-Block Elements Chapter

Explain why Cu+ ion is not stable in aqueous solutions?

Actinoid contraction is greater from element to element than lanthanoid contraction. Why?

On what ground can you say that scandium (Z = 21) is a transition element but zinc (Z = 30) is not?

The outer electronic configuration of copper is 3d10 4s1, yet it is considered transition element. Why?

Why the melting points of transition elements are high?

Why Zn, Cd and Hg are not regarded as transition elements?

Name the first element of 3rd transition series.

Though copper, silver and gold have completely filled sets of d-orbitals yet they are considered as transition metals. Why?

Why are transition elements so named?

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