For the gas phase reaction 2 NO N2 + O2, H = – 43.5 Kcal mol–1which one of the statement below is true for N2 (g) + O2 (g) 2 NO (g)

As the enthalpy of the given reaction is negative, so, the enthalpy of its reverse reaction is positive, hence, it is an endothermic reaction. So, according to the Le-Chatelier’s principle, when the temperature decreases, the reaction is directed in backwards direction for an endothermic reaction. Due to which K of the reaction decreases. Therefore, option (c) is the correct answer.