In chemistry, a physical property differs from a chemical property because physical properties can be observed or determined without changing the substance. Example of this includes color, density or texture while examples of chemical properties include toxicity, flammability, reactivity, oxidation, etc. Density (mass per unit) is classified as part of physical properties because this can be determined by dividing the mass of the substance by its volume which means this property can be measured without altering the substance and therefore it is a physical property.
Manipulation of the independent variable should change the dependent variable, the value of which "depends" on the independent variable's change in value.
