The two aqueous solutions, Q and R, match in concentration when this is expressed in $\text{mol dm}^{-3}$. Solution Q includes $4.0\,\text{g}$ of NaOH in $500\,\text{cm}^3$ of solution. Which one could be solution R? [$A_r$: Na, $23$; O, $16$; H, $1$]
- A$0.2\,\text{mol}$ of Ca(OH)$2$ in $250\,\text{cm}^3$ of solution
- B$0.2\,\text{mol}$ of HCl in $100\,\text{cm}^3$ of solution
- C$0.05\,\text{mol}$ of H$_2$SO$_4$ in $250\,\text{cm}^3$ of solution
- D$0.1\,\text{mol}$ of KOH in $1000\,\text{cm}^3$ of solution