Explain why this is synthesis reaction

Which property of fossils allow scientists to determine the relative rock ages..

What are the phases shown in a and d called?

Achemistry student needs of 40ml diethylamine for an experiment. by consulting the crc handbook of chemistry and physics, the student discovers that the density of diethylamine is 0.7 . calculate the mass of diethylamine the student should weigh out. round your answer to significant digits.