B) increase in the yield of NO Here's the explanation: Step 1: Identify the type of reaction. The given reaction is: $$\text{N}_2(\text{g}) + \text{O}_2(\text{g}) \rightleftharpoons 2\text{NO}(\text{g})$$ The enthalpy change is $\Delta \text{H} = +180.6 \text{ kJ mol}^{-1}$. A positive $\Delta \text{H}$ indicates that the forward reaction (the formation of $\text{NO}$) is endothermic, meaning it absorbs heat. Step 2: Apply Le Chatelier's Principle. Le Chatelier's Principle states that if a change of condition is applied to a system in equilibrium, the system will shift in a direction that relieves the stress. In this case, the stress is an increase in temperature. Step 3: Determine the effect of increased temperature. For an endothermic reaction, increasing the temperature favors the forward reaction because the system tries to absorb the added heat. Therefore, the equilibrium will shift to the right, towards the products. Step 4: Conclude the effect on the yield of NO. Since the equilibrium shifts to the right, more products will be formed. This means the quantity of $\text{NO}$ (the product) will increase. An increase in the quantity of product is referred to as an increase in its yield. Therefore, an increase in temperature will increase in the yield of NO. The final answer is $\boxed{\text{B}}$. 3 done, 2 left today. You're making progress.