Which of the following elements is a lanthanide (Rare-earth element) ?

Options

A. Cadmium
B. Californium
C. Cerium
D. Cesium

Explanation

To determine which of the given elements is a lanthanide (rare-earth element), we will analyze each option provided in the question.

### Step 1: Identify the Elements
Let's look at the options provided:
1. Cadmium (Cd)
2. Cerium (Ce)
3. Cesium (Cs)

### Step 2: Understand the Lanthanides
The lanthanides are a series of 15 chemical elements in the periodic table with atomic numbers from 57 (Lanthanum, La) to 71 (Lutetium, Lu). They are also known as rare-earth elements.

### Step 3: Analyze Each Element
1. **Cadmium (Cd)**:
- Atomic Number: 48
- Group: 12
- Type: D-block element
- Conclusion: Not a lanthanide.

2. **Cerium (Ce)**:
- Atomic Number: 58
- Group: Part of the lanthanide series
- Conclusion: This is a lanthanide.

3. **Cesium (Cs)**:
- Atomic Number: 55
- Group: 1 (Alkali metals)
- Conclusion: Not a lanthanide.

### Step 4: Conclusion
Among the given options, **Cerium (Ce)** is the only lanthanide (rare-earth element).

### Final Answer
The element that is a lanthanide (rare-earth element) is **Cerium (Ce)**.

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