A mixture is made by heating $0.20$ mol of hydrogen gas with $0.15$ mol of iodine gas at $723\,\text{K}$ until equilibrium is reached; the equilibrium mixture then has $0.26$ mol of hydrogen iodide. The equation for the reaction is $\text{H}_2(\text{g}) + \text{I}_2(\text{g}) \rightleftharpoons 2\text{HI}(\text{g})$. Which is the correct equilibrium constant expression for $K_c$?
- A$\dfrac{2 \times 0.26}{0.20 \times 0.15}$
- B$\dfrac{(2 \times 0.26)^2}{0.20 \times 0.15}$
- C$\dfrac{(0.26)^2}{0.07 \times 0.02}$
- D$\dfrac{(0.26)^2}{0.13 \times 0.13}$