$4.0\,\text{g}$ of sodium hydroxide, $\text{NaOH}$, is added to $250\,\text{cm}^3$ of water in a graduated flask. A $25\,\text{cm}^3$ portion of this solution is then titrated using $0.50\,\text{mol dm}^{-3}$ hydrochloric acid. What volume of hydrochloric acid is needed to neutralise the alkali exactly?
- A$10\,\text{cm}^3$
- B$20\,\text{cm}^3$
- C$40\,\text{cm}^3$
- D$200\,\text{cm}^3$