Physical properties are those properties that can be measured or observed and does not imply a change in the composition of the substance for example color and weight. On the hand, chemical properties refer to those that require a chemical change to be observed, this means the substance needs to change to determine the property. Density refers to the mass of a substance of object per unit volume, this means density can be determined by measuring the mass and volume of an object which does not require a change in the substance and are observable and measurable, in the case of flammability, radioactivity and toxicity chemical changes need to occur to determine the property, which makes them chemical properties.
