Aluminium is obtained from alumina:

Answer the following :

(i) Electrolyte used

(ii) Write cathode reaction

(iii) Why anode is replaced

(a) Name the other ion formed when ammonia gas dissolves in water.

(b) Give one test that can be used to detect the presence of the ion produced.

(c) Name the gaseous product formed when dilute nitric acid is added to copper.

State your observations in each of the following:

(a) Dilute hydrochloric acid is added to calcium hydrogen carbonate.

(b) At the cathode, acidified aqueous copper sulphate solution is electrolysed with copper electrodes.

(c) Moist starch iodide paper is introduced into chlorine gas.

(d) Calcium hydroxide is heated with ammonium chloride crystals.

Draw the structure of the stable positive ion formed when sulphuric acid dissolves in water.