Why the impurity of arsenic oxide must be removed before passing the mixture of SO₂ and air through the catalytic chamber?

(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.

In the given equation :

H₂S + 2H₂SO₄ ⟶ S + 2H₂O + SO₂

Identify the role played by conc. H₂SO₄

1. Non-volatile acid
2. Oxidising agent
3. Dehydrating agent
4. None of the above.

Dilute sulphuric acid will produce a white ppt. when added to a solution of:

1. Copper nitrate
2. Zinc nitrate
3. Lead nitrate
4. Sodium nitrate