For the equilibrium of the reaction, HgO(s) $\stackrel{}{⇌}$ Hg(g) + $\frac{1}{2}$O2(g), kP for the reaction at total pressure of P is:

(1) ${\mathrm{K}}_{\mathrm{P}}\mathrm{=}\frac{\mathrm{2}}{{\mathrm{3}}^{3/2}}{\mathrm{p}}^{3/2}$

(2) ${\mathrm{K}}_{\mathrm{P}}\mathrm{=}\frac{\mathrm{2}}{{\mathrm{3}}^{1/2}}{\mathrm{p}}^{1/2}$

(3) ${\mathrm{K}}_{\mathrm{P}}\mathrm{=}\frac{1}{{\mathrm{3}}^{2/3}}{\mathrm{p}}^{3/2}$

(4) ${\mathrm{K}}_{\mathrm{P}}\mathrm{=}\frac{1}{{\mathrm{3}}^{2/3}}\mathrm{p}$