Among the different types of scientific knowledge, are likely to be modified or discarded most frequently. long ago, in the 1600s, scientists discarded the phlogiston theory because .

Among the different types of scientific knowledge  Hypotheses are likely to be modified or discarded most frequently , long ago in the 1600's scientists discarded the phlogiston theory because the new evidence didnt support it.

c-14 is carbon-14, or radiocarbon.   it is a radioactive isotope of carbon with an atomic nucleus containing 6 protons and 8 neutrons.