You use your sense of taste and smell to tell the difference between spinach and an orange. The measurement of mass and other characteristics that can be seen without changing how that object looks are its physical properties. When you look at oranges, you know that they are oranges because of their color, shape, and smell. Mass, color, shape, volume, and density are some physical properties. The answers to the question about the present are physical properties.
Density is an important physical property.
Density is the mass of a substance per unit volume. Volume is the amount of space an object occupies. These are properties that can only be observed by changing the identity of the substance. A piece of paper burns and turns to a black substance. After the flame goes out you can no longer burn the new substance.