For the reaction $CH_{4(g)} + 2O_{2(g)} \rightleftharpoons CO_{2(g)} + 2H_2O_{(l)} \, \Delta H_r = -170.8 \, kJ \, mol^{-1}$,which of the following statements is not true?

• A
  At equilibrium,the concentrations of $CO_{2(g)}$ and $H_2O_{(l)}$ are not equal.
• B
  The equilibrium constant for the reaction is given by $K_P = \frac{p_{CO_2}}{p_{CH_4} \cdot p_{O_2}^2}$.
• C
  Addition of $CH_{4(g)}$ or $O_{2(g)}$ at equilibrium will cause a shift to the right.
• D
  The reaction is exothermic.