To determine which of the given statements is wrong, let's analyze each statement step by step.
### Step-by-Step Solution:
1. **Statement A**: "If the speed of a particle changes, its velocity must change."
- **Analysis**: Speed is a scalar quantity that represents how fast an object is moving, while velocity is a vector quantity that includes both speed and direction. If speed changes, it implies that the magnitude of the velocity vector is changing. Therefore, this statement is **true**.
2. **Statement B**: "If the velocity of a particle does not change, its speed must remain constant."
- **Analysis**: If the velocity (which includes both magnitude and direction) does not change, it means that both the speed and direction are constant. Hence, the speed must also remain constant. This statement is **true**.
3. **Statement C**: "If the speed of a particle does not change, its velocity must remain constant."
- **Analysis**: This statement is **false**. A particle can have a constant speed while changing direction, such as in uniform circular motion. In this case, the speed remains constant, but the velocity changes due to the change in direction. Therefore, this statement is **wrong**.
4. **Statement D**: "If the velocity of a particle changes, its speed may or may not change."
- **Analysis**: This statement is **true**. For example, in uniform circular motion, the velocity changes due to the change in direction, but the speed remains constant. In non-uniform circular motion, both speed and velocity can change. Thus, this statement is correct.
### Conclusion:
The wrong statement among the given options is **Statement C**: "If the speed of a particle does not change, its velocity must remain constant."
