Examples of elements belonging to s, p, d or f-block are given below. Identify the wrong example.

Options

A. s-block element-Caesium
B. p-block element-Barium
C. d-block element-Chromium
D. f-block element-Thorium

Explanation

To solve the question of identifying the wrong example of elements belonging to the s, p, d, or f-block, we will follow these steps:

### Step 1: Identify the elements and their classifications
We have the following elements given in the question:
- S block: Cesium (Cs)
- P block: Barium (Ba)
- D block: Chromium (Cr)
- F block: Thorium (Th)

### Step 2: Determine the atomic numbers and electronic configurations
1. **Cesium (Cs)**:
- Atomic number: 55
- Electronic configuration: [Xe] 6s¹
- Classification: S block (correct)

2. **Barium (Ba)**:
- Atomic number: 56
- Electronic configuration: [Xe] 6s²
- Classification: S block (incorrectly listed as P block)

3. **Chromium (Cr)**:
- Atomic number: 24
- Electronic configuration: [Ar] 3d⁵ 4s¹
- Classification: D block (correct)

4. **Thorium (Th)**:
- Atomic number: 90
- Electronic configuration: [Rn] 6d² 7s²
- Classification: F block (correct)

### Step 3: Identify the wrong example
From the classifications:
- Cesium is correctly classified as an S block element.
- Barium is incorrectly classified as a P block element; it is actually an S block element.
- Chromium is correctly classified as a D block element.
- Thorium is correctly classified as an F block element.

### Conclusion
The wrong example is **Barium (Ba)**, which is incorrectly classified as a P block element when it actually belongs to the S block.

### Final Answer
The wrong example is Barium (Ba).

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