(a)(i) Name two gases that could be used to perform the fountain experiment.

(ii) State the physical property which makes the gases suitable for the experiment in (a)(i)

(b)(i) Define each of the following terms: I. solubility; II. saturated solution.

(ii) State two factors that affect the solubility of a solid in a liquid.

(iii) A salt Z of mass 10.2 g was dissolved in 15.4 cm\(^3\) of distilled water at 40°C. Calculate the solubility of Z in moldm\(^3\) at 40°C. [Mr (Z) = 331].

(c)(i) Town water supplies that have passed through iron pipes contain P and Q ions. In the presence of air, P ions are slowly converted to Q ions.

I. Identify P and Q ions. II. Write a balanced equation for the reaction between P ions, hydrogen ions and oxygen to give Q ions and water.

(ii) Explain briefly a test to confirm the purity of water.

(iii) State the effect of:

I. boiling a temporally hard water. II. adding sodium trioxocarbonate (IV) crystals to permanent hard water;

(iv) Write a balanced equation for the process in (c)(iii)I.