1. Color: The way a substance appears to the human eye. This is determined by the wavelengths of light that the substance absorbs and reflects. For example, a piece of paper is white because it reflects most wavelengths of visible light, while a red apple absorbs all wavelengths except red, which it reflects.

2. Density: The amount of mass contained in a given volume of a substance. It tells us how tightly packed the matter is. For example, a block of lead is much denser than a block of wood of the same size because the atoms in lead are packed more closely together.