Nitric acid, HNO3, is produced from ammonia and oxygen by the consecutive reactions:

4NH3 + 5O2 => 4NO3 + 6H2O
2NO + O2 => 2NO2
3NO2 + H2O => 2HNO3 + NO
How many grams of nitric acid can be obtained from 1.00kg NH3 if NO in the third reaction is not recycled?
Why is it important that NO in the third reaction is not recycled? Other than that, I know what to do. I just want to know the importance of that last piece of information to the calculations.