State the purpose of the 'Contact process'.

In the Contact process

(i) State how you would convert (a) sulphur (b) iron pyrites to sulphur dioxide in the first step of the Contact process.

(ii) State the conditions i.e. catalyst, promoter, temperature and pressure in the catalytic oxidation of sulphur dioxide to sulphur trioxide in the Contact tower. Give a balanced equation for the same.

(iii) State why the above catalytic oxidation reaction supplies energy.

(iv) Give a reason why – vanadium pentoxide is preferred to platinum during the catalytic oxidation of sulphur dioxide.

(v) Give a reason why the catalyst mass is heated electrically – only initially.

(vi) State why sulphur trioxide vapours are absorbed in concentrated sulphuric acid and not in water to obtain sulphuric acid.

State the basic steps with reasons, involved in diluting a beaker of conc. H₂SO₄.

Give reasons why dilute sulphuric acid:

(i) behaves as an acid when dilute.

(ii) is dibasic in nature.