What is the oxidation state of each element in FeBrz?

Asample of the male sex hormone testosterone, c19h28o2, contains 3.88×10^21 atoms of hydrogen.(a) how many atoms of carbon does it contain? (b) how many molecules of testosterone does it contain? (c) how many moles of testosterone does it contain? (d) what is the mass of this sample in grams?

List four observations that indicate that a chemical reaction may be taking place

Calculate the molar mass of aluminum oxide (al2o3). express your answer to four significant figures.