To determine the minimum number of moles of O2 needed to completely react with 16 moles of NH3, we need to use the mole ratios given in the balanced equation.
The balanced equation shows that for every 4 moles of NH3, we need 5 moles of O2. This can be interpreted as the ratio 4 NH3: 5 O2.
To find the number of moles of O2 needed to react with 16 moles of NH3, we can set up a proportion:
(5 moles O2 / 4 moles NH3) = (x moles O2 / 16 moles NH3)
Cross-multiplying the proportion gives us:
5 moles O2 * 16 moles NH3 = 4 moles NH3 * x moles O2
80 moles NH3 = 4 moles NH3 * x moles O2
Simplifying this equation, we find:
80 moles NH3 = x moles O2
Therefore, the minimum number of moles of O2 needed to completely react with 16 moles of NH3 is 80 mol.
So, the correct answer is (4) 80 mol.