Sulphur trioxide, SO₃, is produced from sulphur dioxide, SO₂: 2SO₂(g) + O₂(g) ⇌ 2SO₃(g).

1. aWhat is meant by a reversible reaction? [1]
2. bIf the pressure at equilibrium is increased, will the yield of sulphur trioxide increase, decrease or stay the same? Give a reason. [3]
3. cState two conditions necessary for the production of SO₃ from SO₂ and O₂ in the Contact process. [2]
4. dDescribe how sulphur trioxide, SO₃, is converted into sulphuric acid, H₂SO₄, in the Contact process. [2]
5. eGive two uses of sulphur dioxide, SO₂, other than for the production of sulphuric acid by the Contact process. [2]

You'll mark your own answer against the marking guide when you hand it in.