Which one of the following statements is true?

Options

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 orientation of the axes

Explanation

To determine which statement about scalar quantities is true, let's analyze each option step by step.

### Step 1: Analyze Option A
**Statement:** A scalar quantity is the one that is conserved in a process.

**Analysis:** This statement is false. A scalar quantity can change during a process. For example, distance traveled by an object is a scalar quantity and it can vary as the object moves. Therefore, this option is incorrect.

### Step 2: Analyze Option B
**Statement:** A scalar quantity is the one that can never take negative values.

**Analysis:** This statement is also false. Scalar quantities can take negative values. For instance, temperature is a scalar quantity and can be negative (e.g., -20 degrees Celsius). Thus, this option is incorrect.

### Step 3: Analyze Option C
**Statement:** A scalar quantity is the one that does not vary from one point to another in space.

**Analysis:** This statement is false as well. Scalar quantities can vary from one point to another. For example, gravitational potential is a scalar quantity that changes with position in a gravitational field. Therefore, this option is incorrect.

### Step 4: Analyze Option D
**Statement:** A scalar quantity has the same value for observers with different orientations of the axis.

**Analysis:** This statement is true. Scalar quantities are independent of direction; they have the same value regardless of the orientation of the coordinate system. For example, mass and temperature are scalar quantities that remain constant irrespective of the observer's orientation. Thus, this option is correct.

### Conclusion
After analyzing all options, we find that only **Option D** is true.

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