What do paleontologist call the relatively short time when many new life forms appeared on Earth?

An observation that requires measurement is called quantitative observable or qualitative

How is the way a mixture is combined different from how a compound is combined?

Which factor is likely to impact the possible number of compounds? presence of unlimited number of elements in the periodic table the inability of atoms to align perfectly with other atoms the ability of all elements to react with every other element all elements being equally reactive