For example very rare radioactive chemical elements.
A pure substance
Substance refers to a particular kind of matter with uniform properties, such as an element or compound. It is a fundamental concept in chemistry and is often categorized as either a pure substance or a mixture.
Elements.
substance.
physical: color, shape, texture, smell, ext.
each substance has a density that differ from the densities of other substance.
Water is considered a pure chemical substance. Its mass and properties are similar to many of the other constituent elements.
its transparenta solidpoisonous if eatena kind of rockits hard
No, it is a noun. It refers to the essential nature or the composition of something. It can also refer to whether something has specifics and practicality (His argument has no substance, so it's hard to take him seriously); and it is sometimes a synonym for drugs, as in "substance abuse" (where it is used as a noun adjunct). The adjective forms are "substantial" and substantive.
pure substace
Physical properties are characteristics that can be observed or measured without changing the composition of the substance. When physical properties are altered, such as when a substance changes state (solid to liquid), the basic chemical composition remains the same, indicating that it is still the same kind of matter.
In general use, "substance" refers to a particular kind of matter with uniform properties. In philosophy, it can refer to an individual concrete entity that can exist independently. In the context of addiction, substance refers to drugs or alcohol that are abused or misused.