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NEETChemistryd and f Block Elements

The +3 oxidation state is the most characteristic state for lanthanoids. Considering this, what is the expected chemical behavior of Ce⁴⁺ and Eu²⁺ ions when present in an aqueous solution?

Options

  1. ACe⁴⁺ acts as a strong oxidizing agent, while Eu²⁺ acts as a strong reducing agent.
  2. BCe⁴⁺ acts as a strong reducing agent, while Eu²⁺ acts as a strong oxidizing agent.
  3. CBoth Ce⁴⁺ and Eu²⁺ act as strong oxidizing agents to achieve the +3 state.
  4. DBoth ions are chemically inert in aqueous solution due to their stable f⁰ and f⁷ configurations respectively.

Correct answer

A. Ce⁴⁺ acts as a strong oxidizing agent, while Eu²⁺ acts as a strong reducing agent.

Step-by-step solution

The most stable and characteristic oxidation state for all lanthanoids in aqueous solution is +3 . Cerium in the +4 state has a stable 4f⁰ configuration, but it strongly tends to revert to the more thermodynamically stable +3 state. By gaining an electron ( Ce⁴⁺ + e⁻ Ce³⁺ ), it acts as a strong oxidizing agent. Europium in the +2 state has a stable half-filled 4f⁷ configuration. However, it also tends to achieve the common +3 state by losing an electron ( Eu²⁺ Eu³⁺ + e⁻ ). Thus, it acts as a strong reducing agent.

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