Which one of the following is not the vector quantity?

Options

A. Torque
B. Displacement
C. Velocity
D. Speed

Answer

To determine which of the following is not a vector quantity, we will analyze each option provided: torque, displacement, and velocity.

### Step-by-Step Solution:

1. **Understand Vector and Scalar Quantities**:
- Vector quantities have both magnitude and direction.
- Scalar quantities have only magnitude and no direction.

2. **Analyze Option 1: Torque**:
- Torque is defined as the cross product of force (F) and distance (R) from the pivot point.
- Since torque involves a direction (the direction of the force and the point of rotation), it is a vector quantity.
- **Conclusion**: Torque is a vector quantity.

3. **Analyze Option 2: Displacement**:
- Displacement is defined as the change in position of an object and is calculated as the final position minus the initial position.
- Displacement has both magnitude (the distance between the two points) and direction (from the initial to the final position).
- **Conclusion**: Displacement is a vector quantity.

4. **Analyze Option 3: Velocity**:
- Velocity is defined as the rate of change of displacement with respect to time.
- It can be expressed as displacement divided by time, which also includes both magnitude and direction.
- **Conclusion**: Velocity is a vector quantity.

5. **Identify the Scalar Quantity**:
- Among the options provided, we have established that torque, displacement, and velocity are all vector quantities.
- The question asks for a quantity that is not a vector. The common scalar quantity related to these vectors is speed (which is the magnitude of velocity).
- Therefore, the correct answer is that none of the options provided (torque, displacement, velocity) are scalar quantities.

### Final Answer:
None of the options provided (torque, displacement, velocity) is a scalar quantity. However, if we were to consider speed, which is not listed, that would be the scalar quantity.