How many grams of ammonia (NH3) will be produced when 0.281 grams of nitrogen are combined with hydrogen?

N2 + 3H2 ==> 2NH3

mols N2 = grams/molar mass = ?
Using the coefficients in the balanced equation, convert mols N2 to mols NH3. That will be twice mols N2 = mols NH3.
Then grams NH3 = mols NH3 x molar mass NH3.