Hi Sentpain! Thanks for asking a question here on Brainly.
Solving:
4 NH3 +5 O2 = 4 NO + 6 H2O
☛ Find the ratio for NH3 and O2. That's 4:3
☛ 4.5 x 5 /4 = 5.6
☛ Find the ratio for O2 and H2O. That's 5:6
☛ 3.2 x 6 / 5 = 3.8
Answer: 3.8 mol H2O - choice A
Hope that helps! ★ If you have further questions about this question or need more help, feel free to comment below or leave me a PM. -UnicornFudge aka Nadia