Asubstance that has a little tendency to change into other substance is said to have low?
reactivity, viscosity, density, conductivity

According the science, if a substance has a little tendency to change into another substance is said to have low reactivity. Because the lower the reactivity of a certain substance the lower the chance it will react from a single substance mixed into it.  Reactivity is usually used by a scientist of researchers to define the chemical reactions of two or more substances that combined or interact together. The absence or lack of reactivity is also called as a blunted affect.

No it doesnt because it can be any number.