Why `Eu^(2+)` and `Yb^(2+)` ions in solutions are good reducing agents but an aqueous solution of `Ce^(4+)` is a good oxidising agent?

Explanation

To understand why \( \text{Eu}^{2+} \) and \( \text{Yb}^{2+} \) ions are good reducing agents while \( \text{Ce}^{4+} \) is a good oxidizing agent, we need to analyze their electronic configurations and their tendencies to either lose or gain electrons.

### Step 1: Understand the oxidation states of the elements
- **Europium (Eu)** and **Ytterbium (Yb)** are lanthanides that can exist in multiple oxidation states, primarily \( +2 \) and \( +3 \).
- **Cerium (Ce)** can exist in oxidation states \( +3 \) and \( +4 \).

### Step 2: Analyze the reducing behavior of \( \text{Eu}^{2+} \) and \( \text{Yb}^{2+} \)
- Both \( \text{Eu}^{2+} \) and \( \text{Yb}^{2+} \) are in the \( +2 \) oxidation state and can easily lose one electron to achieve a more stable \( +3 \) oxidation state.
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