Equilibrium constant for the reaction H I 2HI is correctly given by the expression (a) c [H ][I ] K [HI] (b) c [H ][I ] K [2 HI] (c) c [H ][I ] K [HI] (d) c [HI] K [H ][I ]

The given reaction is: 2 2 H I 2HI At equilibrium the equilibrium constant is defined as the ratio of product of concentration of product to the product of concentration of reactants each raise to the power of their respective stoichiometric coefficient. The expression of equilibrium constant for the reaction will be 2 c 2 2 [HI] K = [H ][I ] Hence, the correct answer is option (d)