Ammonia (NH3) react with oxygen (O2) to produce nitrogen monoxide (NO) and water (H2O). Write and balance the chemical equation. How many liter of NO are produced when 2.0 liters of oxygen reacts with ammonia?

Answer 1

4NH3 + 5O2 --> 4NO + 6H2O
I assume you have an excess of NH3 so that O2 is the limiting reagent.
When all are gases you can use a shortcut where liters count as mols. So 5 L O2 will produce 4 L NO.
Scale it down to 2 L O2.