Final answer:
The equilibrium constant for the formation of one mole of NO is the square root of K.
Step-by-step explanation:
The equilibrium constant for a reaction is an expression that relates the concentrations of products and reactants at equilibrium. The equilibrium constant for the reaction N₂ + O₂ ⟶ 2NO is given by K. To find the equilibrium constant for the formation of one mole of NO, we need to consider the balanced chemical equation. In the given reaction, 1 mole of N₂ reacts with 1 mole of O₂ to form 2 moles of NO. Therefore, the equilibrium constant for the formation of one mole of NO is the square root of K. So, the correct answer is d. √K.