The correct option is (a).
Explanation
Physical quantities are properties of a material or system that can be quantified by measurement. They are broadly classified into scalar quantities (having only magnitude) and vector quantities (having both magnitude and direction). Motion is analyzed using parameters such as distance, displacement, speed, and velocity.
Statement-wise Analysis
- Statement 1 is Correct: The magnitude of a physical quantity represents its size or extent. It is expressed as a numerical value accompanied by a unit of measurement. For example, if a car travels 50 km, "50" is the numerical value representing the magnitude of the distance.
- Statement 2 is Incorrect: Displacement is a vector quantity, meaning it possesses both magnitude and direction. It represents the shortest straight-line path between the initial and final positions. Describing it solely by its numerical value (magnitude) is insufficient; direction must also be specified. In contrast, distance is a scalar quantity described solely by its numerical value.
- Statement 3 is Incorrect: Distance is the total length of the path covered by an object during its motion. Since it represents the actual path traveled, it can never be zero for a moving object, nor can it be negative. If an object returns to its starting point, the displacement is zero, but the distance covered is the sum of the entire path length.
Key Takeaway: Distance is a scalar quantity that accumulates with motion and is never zero for a moving body. Displacement is a vector quantity that depends on the initial and final positions and can be zero if the body returns to its starting point.