${K_2}$ for $N{H_3}$ $ \rightleftharpoons $ $\frac{1}{2}{N_2} + \frac{3}{2}{H_2}$
${{K}_{1}}\times {{K}_{2}}=\frac{{{[N{{H}_{3}}]}^{2}}}{[{{N}_{2}}]\,\,{{[{{H}_{2}}]}^{3}}}\times \frac{{{[{{N}_{2}}]}^{{1}/{2}\;}}{{[{{H}_{2}}]}^{{3}/{2}\;}}}{[N{{H}_{3}}]}$
${K_1} \times {K_2} = \frac{1}{{{K_2}}}$; ${K_2} = \frac{1}{{\sqrt {{K_1}} }}$