The equilibrium constants of the following are:

$\begin{array}{cc}{\mathrm{N}}_2+3{\mathrm{H}}_2\rightleftharpoons 2\mathrm{ }{\mathrm{NH}}_3& {\mathrm{K}}_1\\ {\mathrm{N}}_2+{\mathrm{O}}_2\rightleftharpoons 2\mathrm{ }\mathrm{NO}& {\mathrm{K}}_2\\ {\mathrm{H}}_2+\frac{1}{2}{\mathrm{O}}_2\to {\mathrm{H}}_2\mathrm{O}\mathrm{ }& {\mathrm{K}}_3\end{array}$

The equilibrium constant ($\mathrm{K}$) of the reaction:

$2\mathrm{N}\mathrm{H}{}_3+\frac{5}{2}\mathrm{O}{}_2\stackrel{\mathrm{K}}{\rightleftharpoons }2\mathrm{N}\mathrm{O}+3\mathrm{H}{}_2\mathrm{O}$, will be:

• A

  $\frac{{\mathrm{K}}_1\mathrm{ }{\mathrm{K}}_3^3}{{\mathrm{K}}_2}$
• Correct answer
  B

  $\frac{{\mathrm{K}}_2\mathrm{ }{\mathrm{K}}_3^3}{{\mathrm{K}}_1}$
• C

  $\frac{{\mathrm{K}}_2\mathrm{ }{\mathrm{K}}_3}{{\mathrm{K}}_1}$
• D

  $\frac{{\mathrm{K}}_2^3\mathrm{ }{\mathrm{K}}_3}{{\mathrm{K}}_1}$

Hence, the correct answer is option: 'B'.