Verified answer

OK - you equation is balanced. Now let's look at the steps:

1) How many moles if 13.10 g of NH3? Divide by the molecular mass (and you will need this number to at least four significant figures). I get 0.77 moles but I'm only using two sig figs.

2) How many moles of H2 are needed to make 0.77 moles of NH3? Multiply by 3/2.

3) How much does this amount of H2 weight? Multiply by 2 g/mole (again, you will want to use 4 sig figs) to find about 2.3 g. You will need to report your answer to four sig figs, so double check all my math.