A white powder is known to consist of a mixture of magnesium oxide and aluminium oxide. $100\,\text{cm}^3$ of $2\,\text{mol dm}^{-3}\,\text{NaOH(aq)}$ is just enough to make the aluminium oxide in $x$ grams of the mixture dissolve. The reaction taking place is $\text{Al}_2\text{O}_3 + 2\text{OH}^- + 3\text{H}_2\text{O} \rightarrow 2\text{Al(OH)}_4^-$. $800\,\text{cm}^3$ of $2\,\text{mol dm}^{-3}\,\text{HCl(aq)}$ is just enough to make all of the oxide in $x$ grams of the mixture dissolve. The reactions taking place are $\text{Al}_2\text{O}_3 + 6\text{H}^+ \rightarrow 2\text{Al}^{3+} + 3\text{H}_2\text{O}$ and $\text{MgO} + 2\text{H}^+ \rightarrow \text{Mg}^{2+} + \text{H}_2\text{O}$. How many moles of each oxide are present in $x$ grams of the mixture?
- Aaluminium oxide: 0.05, magnesium oxide: 0.25
- Baluminium oxide: 0.05, magnesium oxide: 0.50
- Caluminium oxide: 0.10, magnesium oxide: 0.25
- Daluminium oxide: 0.10, magnesium oxide: 0.50