The oxidation of NH 3 (g) to NO(g) in the Ostwald process must be very carefully controlled

Question:

The oxidation of NH₃(g) to NO(g) in the Ostwald process must be very carefully controlled in terms of temperature, pressure, and contact time with the catalyst. This is because the oxidation of NH₃(g) can yield any one of the products N₂(g), N₂O(g), NO(g), and NO₂(g), depending on conditions. Show that oxidation of NH₃(g) to N₂(g) is the most exothermic of the four possible reactions.