Which of the following statements about radioactivity is are true?

Options

A. It involves outer electrons activity.
B. It is not affected by temperature of pressure.
C. It is an exothermic process.
D. The radioactivity of an element is not affected by any other element compounded by it.

Answer

To determine which statements about radioactivity are true, we will evaluate each option based on the principles of radioactivity.

### Step-by-Step Solution:

1. **Understanding Radioactivity**:
- Radioactivity is the process by which unstable atomic nuclei lose energy by emitting radiation. This can occur in the form of alpha particles, beta particles, or gamma rays. The primary goal of this process is to achieve stability.

2. **Evaluating the Statements**:
- **Option A**: "Radioactivity involves outer electron activity."
- This statement is **false**. Radioactivity is a nuclear phenomenon that involves changes in the nucleus (neutrons and protons), not the outer electrons.

- **Option B**: "Radioactivity is independent of surrounding physical factors like temperature and pressure."
- This statement is **true**. The rate of radioactive decay is not affected by external conditions such as temperature and pressure.

- **Option C**: "Radioactivity is an exothermic process."
- This statement is **true**. Since energy is released during the decay process, it is considered an exothermic reaction.

- **Option D**: "Radioactivity is a nuclear phenomenon."
- This statement is **true**. As mentioned earlier, radioactivity involves changes in the nucleus, making it a nuclear phenomenon.

3. **Conclusion**:
- The true statements about radioactivity are **B, C, and D**.
- The only incorrect statement is **A**.

### Final Answer:
The correct statements about radioactivity are **B, C, and D**. The incorrect statement is **A**.