The equilibrium constant for the reaction $\mathrm{H}_{2}+$ $\frac{1}{2} \mathrm{O}_{2} \rightleftharpoons \mathrm{H}_{2} \mathrm{O}$ at 1 atm and $1500^{\circ} \mathrm{C}$ is given to be $K .$ Of the reactions given below, all at $1500^{\circ} \mathrm{C}$, the reaction that has a different equilibrium constant is
$(a) \mathrm{H}_{2}+\frac{1}{2} \mathrm{O}_{2} \rightleftharpoons \mathrm{H}_{2} \mathrm{O}$ at 5 atm
$(b) 2 \mathrm{H}_{2}+\mathrm{O}_{2} \rightleftharpoons 2 \mathrm{H}_{2} \mathrm{O}$ at 1 atm
$(c) \mathrm{H}_{2}+\mathrm{O}_{2} \rightleftharpoons \mathrm{H}_{2} \mathrm{O}+\frac{1}{2} \mathrm{O}_{2}$ at 2 atm
$(d) \mathrm{H}_{2}+\frac{1}{2} \mathrm{O}_{2}+3 \mathrm{N}_{2} \rightleftharpoons \mathrm{H}_{2} \mathrm{O}+3 \mathrm{N}_{2} $ at $5 \mathrm{atm}$
$(e) \mathrm{H}_{2}+\frac{1}{2} \mathrm{O}_{2}+3 \mathrm{N}_{2} \rightleftharpoons \mathrm{H}_{2} \mathrm{O}+3 \mathrm{N}_{2} \quad$ at 1 atm