Which of the following ages cannot be determined by radioactive carbon dating?

Options

A. Remains of the animal
B. Samples of rock from old mountain
C. A 100- years-old tree
D. An old piece of wood

Answer

To solve the question of which of the following ages cannot be determined by radioactive carbon dating, we need to understand the principles of radiocarbon dating and the types of materials it can be applied to.

### Step-by-Step Solution:

1. **Understand Radiocarbon Dating**:
- Radiocarbon dating, or carbon-14 dating, is a method used to determine the age of organic materials. It relies on the decay of carbon-14, a radioactive isotope of carbon, which is found in all living organisms.

2. **Identify Organic Materials**:
- Radiocarbon dating can only be used on materials that were once part of living organisms. This includes things like wood, bone, and other organic materials.

3. **Analyze Each Option**:
- **Option 1: Remains of the animal**:
- Since animals are living organisms, their remains can be dated using radiocarbon dating.
- **Conclusion**: This option can be determined by radiocarbon dating (incorrect answer).

- **Option 2: Samples of rock from old mountain**:
- Rocks are inorganic materials and do not come from living organisms. Therefore, their age cannot be determined by radiocarbon dating.
- **Conclusion**: This option cannot be determined by radiocarbon dating (correct answer).

- **Option 3: A hundred years old tree**:
- A tree is a living organism, and its age can be determined through radiocarbon dating as long as it is still organic material.
- **Conclusion**: This option can be determined by radiocarbon dating (incorrect answer).

- **Option 4: An old piece of wood**:
- Wood comes from trees, which are living organisms. Thus, the age of the wood can be determined using radiocarbon dating.
- **Conclusion**: This option can be determined by radiocarbon dating (incorrect answer).

4. **Final Conclusion**:
- The only option that cannot be determined by radioactive carbon dating is **samples of rock from old mountain**.

### Final Answer:
The age that cannot be determined by radioactive carbon dating is **samples of rock from old mountain**.