(a)[2]
State the operating conditions used in the contact process: temperature, pressure and catalyst.
(b)[2]
Describe and explain how increasing the concentration of oxygen changes the rate of the reaction $2\text{SO}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{SO}_3(g)$.
(c)[1]
Describe one further benefit of using a catalyst in an industrial process.
(d)[2]
Calculate the percentage by mass of potassium in potassium sulfate, $\text{K}_2\text{SO}_4$.