Pleaseee …… I’m begging, help

An example of technology is the a. addition of a side group to an organic molecule during synthesis. b. use of a new antibiotic to fight an infection. c. measurement of iron concentration in a water sample. d. study of atomic fusion reactions

Nuclear fusion is the source of energy for stars. besides hydrogen, which other element is most likely also common in stars?

Write the empirical chemical formula of calcium with a mass percent of 38.8, phosphorus with a mass percent of 20.0, and oxygen with a mass percent of 41.3.