(a) Name the catalyst which helps in the conversion of sulphur dioxide to sulphur trioxide in step C.

(b) In the Contact process for the manufacture of sulphuric acid, sulphur trioxide is not converted to sulphuric acid by reacting it with water. Instead a two steps procedure is used. Write the equations for the two steps involved in D.

(c) What type of substance will liberate sulphur dioxide from sodium sulphite in step E?

(d) Write the equation for the reaction by which sulphur dioxide is converted to sodium sulphite in step F.

(a) Vanadium pentoxide

$2\text{SO}$2 + \text{O}2 \xrightleftharpoons [450-500\text{\degree C }/1 - 2 \text{ atmos}]{\text{V}2\text{O}5} 2\text{SO}_3 + \text{45 K cals}

(b) Main reactions of this process are:

SO₃ + H₂SO₄ (conc.) ⟶ H₂S₂O₇ (oleum)

H₂S₂O₇ + H₂O ⟶ 2H₂SO₄

(c) Dilute Sulphuric acid

Na₂SO₃ + H₂SO₄ ⟶ Na₂SO₄ + H₂O + SO₂[g] ↑

d) 2NaOH + SO₂ ⟶ Na₂SO₃ + H₂O