If the reaction of 1*0 mol NH3 (g) and 1-0 mol 02 (g) 4NH3 (g) + 502 (g) —>4NO (g) + 6H20 [I) is carried to completion, then

The balanced chemical equation 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(l) indicates a stoichiometric mole ratio of 4:5 between ammonia and oxygen. To react 1.0 mole of NH3, 1.25 moles of O2 are required (1.0!! 5/4). Conversely, to react 1.0 mole of O2, only 0.8 moles of NH3 are needed (1.0!! 4/5). Since only 1.0 mole of each reactant is provided, oxygen (O2) acts as the limiting reagent because it will be exhausted first. Upon completion, all 1.0 mole of O2 is consumed. Calculations show that 1.0 mole of O2 produces 0.8 moles of NO (1.0!! 4/5) and 1.2 moles of H2O (1.0!! 6/5), while 0.2 moles of NH3 remain in excess. Therefore, only option 1 is correct.