Does anyone know how to write on a pdf file? I have to do an assignment for chemistry, but i don’t know how to write on it through my laptop. I downloaded it but it still doesn’t really let me type or write on it. Help?

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?

Different isotopes indicate that an element will have different numbers of

Which rate indicates the number of children that would be born per woman if she were to live to the end of her child bearing years