Final answer:
The overall order of the reaction H₂(g) + 2NO(g) → N₂O(g) + H₂O(g) is 3.
Step-by-step explanation:
The overall order of a reaction can be determined by adding up the orders with respect to each reactant. In the given reaction, H₂(g) + 2NO(g) → N₂O(g) + H₂O(g), the rate is given as rate = k[NO]²[H₂]. The order with respect to NO is 2, and the order with respect to H₂ is 1. To find the overall order, we add these orders together: 2 + 1 = 3. Therefore, the overall order of the reaction is 3.