One scientist kept 20 grams of a radioactive material in a container. What will be the mass of the radioactive material left in the container after 2 half lives?

40 grams
4 grams
10 grams
5 grams

Which statement best explains why cells were observed in more detail using a compound microscope than a simple microscope? a compound microscope has greater magnification ability than a simple microscope. the compound microscope was invented before the simple microscope. a compound microscope is much easier to manufacture than a simple microscope. compound microscopes were more common than simple microscopes.