Which of the following lanthanoids shows `+4` oxidation state to acquire noble gas configuration ? (Atomic number : `La=57`, `Ce=58`, `Eu=63` and `Yb=70`)

Options

A. Eu
B. Ce
C. Yb
D. La

Explanation

To determine which lanthanoid shows a +4 oxidation state to acquire a noble gas configuration, we will analyze the electronic configurations of the given lanthanoids: La (Lanthanum), Ce (Cerium), Eu (Europium), and Yb (Ytterbium).

### Step 1: Write the electronic configurations of the lanthanoids.

1. **Lanthanum (La, Z=57)**:
- Electronic configuration: [Xe] 6s² 5d¹
- This means it has 2 electrons in the 6s orbital and 1 electron in the 5d orbital.

2. **Cerium (Ce, Z=58)**:
- Electronic configuration: [Xe] 6s² 5d¹ 4f¹
- This means it has 2 electrons in the 6s orbital, 1 in the 5d orbital, and 1 in the 4f orbital.

3. **Europium (Eu, Z=63)**:
- Electronic configuration: [Xe] 6s² 4f⁷
- This means it has 2 electrons in the 6s orbital and 7 in the 4f orbital.

4. **Ytterbium (Yb, Z=70)**:
- Electronic configuration: [Xe] 6s² 4f¹⁴
- This means it has 2 electrons in the 6s orbital and 14 in the 4f orbital.

### Step 2: Determine the ability to achieve +4 oxidation state.

To achieve a +4 oxidation state, an element must lose 4 electrons. We will analyze each lanthanoid:

1. **Lanthanum (La)**:
- It has only 3 valence electrons (2 from 6s and 1 from 5d). It cannot lose 4 electrons, so it cannot exist in the +4 state.

2. **Cerium (Ce)**:
- It has 4 valence electrons (2 from 6s, 1 from 5d, and 1 from 4f). It can lose 4 electrons (2 from 6s, 1 from 5d, and 1 from 4f) to achieve a +4 oxidation state. The resulting configuration would be [Xe], which is a noble gas configuration.

3. **Europium (Eu)**:
- It has 9 valence electrons (2 from 6s and 7 from 4f). It can lose 2 electrons to achieve +2 oxidation state (which is stable), but losing 4 electrons would not lead to a noble gas configuration.

4. **Ytterbium (Yb)**:
- It has 16 valence electrons (2 from 6s and 14 from 4f). It can lose 2 electrons to achieve +2 oxidation state (which is stable), but losing 4 electrons would not lead to a noble gas configuration.

### Conclusion:
Only **Cerium (Ce)** can achieve the +4 oxidation state and acquire the noble gas configuration of Xenon.

### Final Answer:
**Cerium (Ce) shows +4 oxidation state to acquire noble gas configuration.**

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