A sample of rock has a mass of $2.00\,\text{g}$. It contains calcium carbonate, but no other basic substances. It completely neutralises $36.0\,\text{cm}^3$ of $0.500\,\text{mol dm}^{-3}$ hydrochloric acid. What is the percentage by mass of calcium carbonate in the $2.00\,\text{g}$ sample of rock?
- A22.5%
- B45.0%
- C72.0%
- D90.1%