The material having minimum work function is

Options

A. copper
B. silver
C. gold
D. cesium

Answer

To solve the question regarding which material has the minimum work function, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Concept of Work Function**:
- The work function (W) is defined as the minimum energy required to remove an electron from the surface of a material. It is a characteristic property of metals and varies from one material to another.

2. **Identify the Given Options**:
- The options provided are:
- A) Copper
- B) Silver
- C) Gold
- D) Cesium

3. **Analyze the Properties of Each Material**:
- **Copper**: A common metal with a moderate work function.
- **Silver**: Similar to copper but generally has a slightly higher work function.
- **Gold**: Has a higher work function than both copper and silver.
- **Cesium**: Notably, cesium has a very low melting point (around room temperature), which means it is in a liquid state at or near room temperature. This property suggests that electrons can be removed more easily from its surface.

4. **Determine the Material with the Minimum Work Function**:
- Among the options, cesium stands out due to its low melting point, indicating that it has a lower binding energy for its electrons compared to the other metals listed. Therefore, it is expected to have the minimum work function.

5. **Conclusion**:
- The material with the minimum work function is **D) Cesium**.