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NEET CHEMISTRYThe d-and f-Block ElementsMedium

Question

The incorrect statement regarding the lanthanons is:

A

Europium shows +2+2 oxidation state

B

The basicity decreases as the ionic radius decreases from Pr\text{Pr} to Lu\text{Lu}

C

All the lanthanons are much more reactive than aluminium

D

Ce\text{Ce} (+4+4) solutions are widely used as oxidising agents in volumetric analysis

Step-by-Step Solution

In their chemical behaviour, the earlier members of the lanthanoid series are quite reactive, similar to calcium. However, with increasing atomic number, their reactivity decreases and they behave more like aluminium. Thus, the statement that all lanthanons are much more reactive than aluminium is incorrect.

The other statements are correct:

  • Europium (Eu\text{Eu}) can exhibit a +2+2 oxidation state due to the stability of its half-filled f7f^7 configuration.
  • Due to lanthanoid contraction, the ionic radius of Ln3+\text{Ln}^{3+} ions decreases steadily from La\text{La} to Lu\text{Lu}. This decrease in size increases the covalent character of the Ln−OH\text{Ln}-\text{OH} bond, thereby decreasing the basicity of their hydroxides.
  • Ce4+\text{Ce}^{4+} is a strong oxidising agent because it tends to accept an electron to revert to the more stable +3+3 oxidation state. It is widely used as a standard oxidant in volumetric analysis.

Exam Context & Concepts Covered

This question aligns with the NEET CHEMISTRY syllabus, specifically targeting concepts from The d-and f-Block Elements. Mastering this topic is crucial for scoring well in the upcoming medical entrance examinations. Solving conceptually related problems will help you understand the nuances of these concepts and improve your problem-solving speed.

CHEMISTRYThe d-and f-Block Elementsincorrectstatementregardinglanthanons

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A.$d^5$ to $d^2$ configuration
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A.The π-bonding involves the overlap of d-orbitals of oxygen with d-orbitals of manganese.
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The incorrect statement among the following is:

A.Lanthanoids are good conductors of heat and electricity.
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