A mixture containing 0.200 mol of sulfur dioxide and 0.200 mol of oxygen is added to a sealed 1.00 dm$^3$ container. The gases are then left to react until equilibrium is established. $ 2\text{SO}_2 + \text{O}_2 \rightleftharpoons 2\text{SO}_3 $ When equilibrium is reached, the container contains 0.100 mol of $\text{SO}_3$. Calculate the value of $K_c$.
- A$0.150\ \text{mol dm}^{-3}$
- B$0.800\ \text{mol dm}^{-3}$
- C$1.25\ \text{mol}^{-1}\text{dm}^3$
- D$6.67\ \text{mol}^{-1}\text{dm}^3$