(a(i))[1]
Deduce the percentage by mass made up by other elements in the oceans.
(a(ii))[1]
Which element occurs in the Earth’s crust at the highest percentage by mass?
(a(iii))[2]
Give two key differences in the percentage by mass of the elements in the Earth’s crust and in the oceans.
(b(i))[1]
Name an ore that contains aluminium oxide.
(b(ii))[2]
Predict the products of the electrolysis of molten aluminium oxide at: • the positive electrode • the negative electrode
(b(iii))[1]
Suggest why aluminium is extracted by electrolysis instead of by reduction with carbon.