Which statement best defines a physical quantity?

### Why this is right A physical quantity is a property that can be measured and reported objectively. Its numerical value tells you how much there is, and its unit tells you what measurement standard that number uses. ### The concept Examples include $30\ \text{min}$, $10\ \text{m}$, and $50\ \text{kg}$. The number without its unit is incomplete because it does not say whether the measurement is time, length, or mass. Physical quantities let scientists compare observations using shared measurement standards. ### The other options - **B. A subjective description that cannot be measured**: this describes a qualitative judgment, not a physical quantity. - **C. A unit used only for biological measurements**: a unit is part of a quantity, but physical quantities are used across physics and other sciences. - **D. A mathematical operation performed on two values**: this describes a calculation, not a measurable property. ### Terms - **Physical quantity**: a measurable property reported with a numerical value and a unit. - **Unit**: an agreed standard used to express a measurement. ### Remember A reported physical measurement needs both a number and a unit.