State one property of aluminium oxide that explains why an aluminium object does not react with cold water until the aluminium oxide layer is removed.
Write an equation, with state symbols, for the reaction between aluminium oxide and excess $\text{NaOH(aq)}$.
Name one other Period 3 element that also produces bubbles of gas when added to cold water.
State the formula of the salt of another Period 3 element that also decomposes on heating to give a brown gas.
State the maximum oxidation number of aluminium and phosphorus in these solid chloride salts.
State why the maximum oxidation number of aluminium is not the same as that of phosphorus.
Write an equation for the reaction between solid phosphorus chloride and excess water.
Name the type of reaction that happens when aluminium chloride is added to water.
Explain why the solution formed after aluminium chloride is added to water has a pH of $1$-$2$.