If 30.0 g of H2 were used, how many grams of NH3 would be made?

Answer 1

N2 + 3H2 ==> 2NH3
Convert 30.0 g H2 to moles.
Convert moles H2 to moles NH3.
Convert moles NH3 to grams.
Here is a link if you get stuck.
http://www.jiskha.com/science/chemistry/stoichiometry.html

Answer 2

10 mole of NH3

Answer 3

507 g; use proportions with value to find as the x thus on top. 34.088x30/2.016