Choose the correct statement from the following:

Options

A. The magnitude of velocity of a particle is equal to its speed at that instant
B. The magnitude of the average velocity in an interval is equal to its average speed in that speed in that interval
C. It is possible to have a situation in which the speed in an interval is zero
D. It is possible to have a situation which the instantaneous speed of particle is always zero but the average speed is not zero

Answer

To solve the question, we need to analyze the statements provided and determine which one is correct based on our understanding of motion, speed, and velocity.

### Step-by-Step Solution:

1. **Understanding Velocity and Speed**:
- Velocity is a vector quantity that has both magnitude and direction.
- Speed is a scalar quantity that only has magnitude and is the absolute value of the velocity.

2. **Analyzing the First Statement**:
- "The magnitude of velocity of a particle is equal to its speed at that instant."
- This statement is true because the speed of a particle is defined as the magnitude of its velocity vector.

3. **Analyzing the Second Statement**:
- "The magnitude of the average velocity in an interval is equal to the average speed in that interval."
- This statement is generally false. Average velocity is displacement divided by time, while average speed is distance divided by time. They can be equal only in specific cases (e.g., straight-line motion without changing direction).

4. **Analyzing the Third Statement**:
- "It is possible to have a situation in which the speed in an interval is 0."
- This statement is false. Speed is defined as distance traveled over time. If a particle does not move, the distance is zero, leading to a speed of zero. However, in any interval where there is movement, the speed cannot be zero.

5. **Analyzing the Fourth Statement**:
- "It is possible to have a situation in which the instantaneous speed of a particle is always 0 but the average speed is not 0."
- This statement is also false. If the instantaneous speed is always 0, it means the particle is not moving at all, which would result in an average speed of 0 as well.

6. **Conclusion**:
- The only correct statement is the first one: "The magnitude of velocity of a particle is equal to its speed at that instant."

### Final Answer:
The correct statement is: **The magnitude of velocity of a particle is equal to its speed at that instant.**