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 in each will increase
B. resistance in each will decrease
C. the resistance of copper will increase while that of germanium will decrease
D. the resistance of copper will decrease while that of germanium will increase

Answer

To solve the question regarding the behavior of copper and germanium when cooled from room temperature to 80 K, we need to analyze the properties of both materials concerning their electrical resistance at different temperatures.

### Step-by-Step Solution:

1. **Identify the Materials**:
- Copper is a metal.
- Germanium is a semiconductor.

2. **Understand Resistance Behavior in Metals**:
- In metals like copper, as the temperature decreases, the resistance typically decreases. This is because the lattice vibrations decrease, allowing electrons to move more freely.

3. **Understand Resistance Behavior in Semiconductors**:
- In semiconductors like germanium, the behavior is different. As the temperature decreases, the number of charge carriers (electrons and holes) decreases, leading to an increase in resistance. This is because fewer charge carriers are available to conduct electricity.

4. **Cooling from Room Temperature to 80 K**:
- When both materials are cooled to 80 K:
- The resistance of copper will **decrease**.
- The resistance of germanium will **increase**.

5. **Evaluate the Statements**:
- The statements to evaluate are:
1. Increase in temperature will increase resistance in each.
2. Increase in temperature will decrease the resistance of copper.
3. The resistance of copper will increase while that of germanium will decrease.
4. The resistance of copper will decrease while that of germanium will increase.

6. **Identify the Wrong Statements**:
- Statement 1 is incorrect because an increase in temperature does not increase resistance in germanium.
- Statement 2 is correct because an increase in temperature decreases the resistance of copper.
- Statement 3 is incorrect because the resistance of copper decreases, while that of germanium increases.
- Statement 4 is correct as it accurately describes the behavior of both materials.

### Conclusion:
The wrong statements are:
- Statement 1: "Increase in temperature will increase resistance in each."
- Statement 3: "The resistance of copper will increase while that of germanium will decrease."