Which of the following metal is the most difficult to extract from its oxide?

Options

A. `Cs`
B. `Ca`
C. `Mg`
D. `Ag`

Answer

To determine which of the following metals is the most difficult to extract from its oxide, we will analyze the reactivity and extraction processes of the given metals: cesium (Cs), calcium (Ca), magnesium (Mg), and silver (Ag).

### Step-by-Step Solution:

1. **Identify the Metals and Their Groups**:
- Cesium (Cs) is an alkali metal from Group 1.
- Calcium (Ca) and Magnesium (Mg) are alkaline earth metals from Group 2.
- Silver (Ag) is a transition metal from the d-block.

2. **Understand Reactivity Trends**:
- Alkali metals (like cesium) are known for their high reactivity due to their tendency to lose their single valence electron easily.
- Alkaline earth metals (like calcium and magnesium) are also reactive, but they have two valence electrons, making them less reactive than alkali metals.
- Transition metals (like silver) have variable oxidation states and are generally less reactive than alkali and alkaline earth metals.

3. **Consider the Extraction Process**:
- The extraction of metals from their oxides typically involves reduction processes. The more reactive a metal is, the more difficult it is to extract it from its oxide because it tends to remain in the oxide form rather than being reduced to the elemental form.
- Cesium, being the most reactive of the group, forms stable oxides that are difficult to reduce.

4. **Evaluate Each Metal**:
- **Cesium (Cs)**: Highly reactive, forms stable oxides, making extraction difficult.
- **Calcium (Ca)**: Reactive but less so than cesium; extraction is feasible.
- **Magnesium (Mg)**: Reactive but can be extracted using thermochemical methods.
- **Silver (Ag)**: Less reactive, can be extracted relatively easily from its oxides.

5. **Conclusion**:
- Based on the analysis, cesium is the most difficult metal to extract from its oxide due to its high reactivity and the stability of its oxide.

### Final Answer:
**Cesium (Cs) is the most difficult metal to extract from its oxide.**