Question

Which one of the following statements is true?
A. A scalar quantity is the one that is conserved in a process.
B. A scalar quantity is the one that can never take negative values.
C. A scalar quantity is the one that does not vary from one point to another in space.
D. A scalar quantity has the same value for observers with different orientations of the axes.

Answer 1

Let's get a fundamental understanding of scalar quantity before we get into the question. Physical quantities that are characterised only by their magnitude or size are known as scalar quantities. To answer the question, we'll look at each of the statements given above and choose the best option.

Complete answer:
(A) A scalar quantity is the one that is conserved in a process:-
The claim is untrue. Because kinetic energy (a scalar quantity) is not conserved in inelastic collisions, this is the case.
(B) A scalar quantity is the one that can never take negative values:-
The claim is untrue. Because temperature (a scalar quantity) can be negative, this is the case.
(C) A scalar quantity is the one that does not vary from one point to another in space:-
The claim is untrue. This is due to the fact that gravitational potential energy (a scalar quantity) varies from one location in space to the next.
(D) A scalar quantity has the same value for observers with different orientations of the axes:-
Because the value of a scalar does not change with the orientation of the axes, the assertion is correct.
The definition of a scalar quantity never mentions its variation from one location to another because it always has the same value, but the value changes for the observers due to different view-points.

Note:
It's worth mentioning that the term scalar was initially used to refer to any number that could be measured on a scale. Consider the numbers on a thermometer scale, which are used to measure temperature. These values need a positive or negative sign to indicate whether they are larger or less than zero, but they don't need a direction indicator because they don't have a component that indicates their position in space.