For the reaction, 
${\mathrm{CH}}_4\left(\mathrm{g}\right)+2{\mathrm{O}}_2\left(\mathrm{g}\right)\rightleftharpoons {\mathrm{CO}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right){\mathrm{\Delta }}_{\mathrm{r}}\mathrm{H}=-170.8{\mathrm{kJmol}}^{-1}$
Which of the following statements is not true?

The equilibrium constant for the reaction is given by ${\mathrm{K}}_{\mathrm{p}}=\frac{\left[{\mathrm{CO}}_2\right]}{\left[{\mathrm{CH}}_4\right]{\left[{\mathrm{O}}_2\right]}^2}$

The reaction is exothermic

At equilibrium, the concentrations of CO₂(g) and H₂O(l) are not eqtral

Addition of CH₄ (g) or O₂(s) at equilibrium will cause a shift to the right