For this question, assume that every gas behaves ideally. Hydrogen and iodine undergo a reversible reaction shown below. The mixture attains dynamic equilibrium. $\text{H}_2(\text{g}) + \text{I}_2(\text{g}) \rightleftharpoons 2\text{HI}(\text{g}) \qquad \Delta H = -9.5\,\text{kJ mol}^{-1}$ Which statement must be correct for the $K_p$ of this equilibrium to remain constant?
- AThe partial pressures of $\text{H}_2$, $\text{I}_2$ and $\text{HI}$ are equal.
- BThe external pressure is constant.
- CThe forward and reverse reactions have stopped.
- DThe temperature is constant.