What is the concentration of a solution prepared by dissolving $31.8\,\text{g}$ of sodium carbonate, $\text{Na}_2\text{CO}_3$, in water to produce $250\,\text{cm}^3$ of solution?
- A$0.075\,\text{mol dm}^{-3}$
- B$0.30\,\text{mol dm}^{-3}$
- C$1.2\,\text{mol dm}^{-3}$
- D$1.5\,\text{mol dm}^{-3}$