(a)(i) Contract process
(ii) Vanadium (v) oxide (V\(_2\)O\(_5\))
(iii) 2SO\(_{2(g)}\) + O\(_{2(g)}\) \(\rightleftharpoons\) 2SO\(_{3(g)}\)
SO\(_{3(g)}\) + H\(_2\)SO\(_4\)\(_{(/)}\) \(\to\) H\(_2\)S\(_2\)O\(_7\)
H\(_2\)S\(_2\)O\(_7\)\(_{(/)}\) + H\(_2\))\(_{(/)}\) \(\to\) 2H\(_2\)SO\(_{4(aq)}\)

(b)(i) Dehydration is the removeal of the element of water from a compound with change in the chemical composition of the compcu while drying is the removal of associated water from a substance without affecting it chemical composition.
(ii) Concentrated H\(_2\)SO\(_4\) reacts with ammonia to form ammonium tetraoxosulphate (VI)
(iii) CaO or silica gel.

(c)(i) I. lead chloride (PbCl\(_2\))
II. K\(_2\)CO\(_3\) or Na\(_2\)CO\(_3\)
III. ZnO or Al\(_2\)O\(_3\)

(ii) I - Reaction of an acid with base (neutralization reaction)
- Reactiction of an acid with a metal
- Reaction of an acid with trioxocarbonate (IV)
- Double decomposition
- Direct combination of its constituent element
- A metal with halogens

(iii) - Evaporation
- Crystallization

(d)(i) Gay lussac's Law of coming volumes states that when gases react, they do so in volumes which are in simple ratio to one another and to the volumes of the products if gaseous, provided that the temperature and pressure remains constant.
(ii) C\(_2\)H\(_{4(g)}\) + 3O\(_{2(g)}\) \(\to\) 2H\(_2\)O + 2Cl\(_{2(g)}\)
1 cm\(^3\) of ethene requires 3cm\(^3\) of oxygen
12.5cm\(^3\) of ethene will require 3 x 12.5cm\(^3\) of oxygen = 37.5cm\(^3\)