4NH3(g) + 5O2(g) → 6H2O(g) + 4NO(g)
0.632/17 x 4 = 0,00929411765 moles of NH3.
0.438/32 x 5 = 0,0027375 moles of O2.
0.0027375 x 4 x 30 = 0,3285 g of NO.