A piece of copper and the other of germanium are cooled from the room temperature to 80 K, then which of the following would be wrong statements?

Options

A. Resistance of each increases
B. Resistance of each decreases
C. Resistance of copper increases while that of germanium decreases
D. Resistance of copper decreases while that of germanium increases

Answer

To solve the question, we need to analyze the behavior of copper and germanium when cooled from room temperature to 80 K. Let's break down the solution step by step:

### Step 1: Understand the Properties of Copper
- Copper is a **good conductor** of electricity.
- As temperature decreases, the resistance of conductors typically **decreases** because the thermal agitation of the atoms reduces, allowing electrons to flow more freely.

### Step 2: Understand the Properties of Germanium
- Germanium is a **semiconductor**.
- When the temperature decreases, the resistance of semiconductors typically **increases**. This is because the number of charge carriers (electrons and holes) decreases as temperature drops, leading to higher resistance.

### Step 3: Analyze the Statements
Now, we need to evaluate the statements provided in the question regarding the resistance of copper and germanium:

1. **Statement 1**: Resistance of each will increase.
- This is **wrong** because the resistance of copper decreases while the resistance of germanium increases.

2. **Statement 2**: Resistance of each is decreased.
- This is **wrong** because while the resistance of copper decreases, the resistance of germanium increases.

3. **Statement 3**: Resistance of copper increases.
- This is **wrong** because the resistance of copper actually decreases.

4. **Statement 4**: Resistance of copper decreases while that of germanium increases.
- This is **correct**. The resistance of copper decreases and the resistance of germanium increases.

### Conclusion
Based on the analysis, the **wrong statements** are:
- Statement 1
- Statement 2
- Statement 3

The **correct statement** is Statement 4.