(a)Give two reasons why aluminium is preferred to copper for making overhead electric cables.

(ii) Describe briefly the electrolytic extraction of aluminium from purified bauxite.

(b) The diagram below represents an electrolytic cell used for the purification of copper.

(i) Which of the electrodes I and II increases in mass during the electrolysis? Give reasons for your answers

(ii) State with reason the site of oxidation

(iii) Identify III and explain why its colour does not change in intensity during the electrolysis.

(c) Calculate the current in amperes that will deposit 8.00 g of calcium from used CaCl\(_2\) in 1 hour 15 minutes. [Ca = 40.0; 1 Faraday = 96500C]

(a) Mention one oxide in each case, which

(i) used in bleaching

(ii) is a redish-brown gas

(iii) reacts with NaOH and also with HCI;

(iv) dissolves in water to give a solution with pH greater than 7;

(v) oxidizes hot, concentrated HCI to chlorine

(b)(i) State three methods that can be used to removo hardness in a sample of water that contains calcium hydrogentrioxocarbonate (IV).

(ii) Explain with the aid of appropriate equation, why it is not advisable to build a house with limestone in an environment polluted by sulphur (IV) oxide.

(c)(i) List two compounds of potassium which yield oxygen when heated strongly

(ii) Calculate the amount (in moles) of gas which occupies 250 cm\(^3\) at s.t.p. [1 mole of gas occupies 22.4 dm\(^3\) at s.t.p]

(iii) If 250 cm\(^3\) of a gas at s.t.p. is heated to 27°C at constant pressure, calculate its new volume.

(iv) Explain in terms of the collision theory what happens as a gas is heated at constant pressure.

(a) State the role of each of the following substances in the treatment of river water for town supply (i) Sand bed. (ii) Alum (iii) Chlorine

(b)(i) Give three major uses of H\(_2\)SO\(_4\)

(ii) Explain the following observation: A strip of blue litmus paper dropped into concentrated H\(_2\)SO\(_4\) becomes charred whereas in dilute H\(_2\)SO\(_4\), it turns red and is not charred.

(iii) Write an equation to show how concentrated H\(_2\)SO\(_4\) reacts with zinc.

(c)(i) List two gaseous pollutants that can be generated by burning coal.

(ii) Explain why coal burns more easily when it is broken into pieces than when it is in lump form.

(ii) What gas is responsible for most of the explosions in coal mines?

(iv) Name: the non-volatile residue left behind after the destructive distlillation of coal

(d)(i) What is meant by allotropy?

(ii) Name two crystalline allotropes of carbon

(iii) Name two elements apart from carbon, which exhibit allotropy

(iv) It is now known that carbon has an allotropic form called fullerene, containing molecules of formula C\(_{60}\). Calculate the mass of one mole of these molecules [C = 12]

All your burette readings (initial and final), as well as the size of your pipette, must be recorded but no account of experimental procedure is required. All calculations must be done in your answer book. A is a solution of HCl containing 7.30g dm\(^{-3}\), B is a solution of X\(_2\)CO\(_{3}\) containing 10.6 gdm\(^{-3}\)

(i) Put A into your burette and titrate readings against 20.0 cm\(^3\) or 25.0cm\(^3\) portions of B using methyl orange as indicator. Tabulate your burette reading and calculate the average volume of A used. The equation for the reaction involved in the titration is ;

X\(_2\)CO\(_{3(aq)}\) + 2HCl\(_{(aq)}\) \(\to\) 2XCl\(_{(aq)}\) + H\(_2\)O\(_{(l)}\) + CO\(_{2(g)}\)

(ii) From your results and the information provided above, calculate the (i) concentration or A in mol dm\(^{3-}\)

Credit will be given for strict adherence to instructions, for observations precisely recorded, and for accurate interference. All tests, Observations and inferences must be clearly entered in your answer book, in ink at the time they are made. C and D are aqueous solutions of simple salt and an inorganic compound respectively. Carry out the following exercises on C and D. Record your observations and identify the gasses evolved. State the conclusion and draw from the result in the test and add sodium hydroxide in excess.

(b)(i) Test D with litmus paper 

(ii) Put about 5cm\(^3\) of D in a test tube and add sodium hydroxide solution in drops and then in excess 

(iii) Add about 1cm\(^3\) of the soap solution provided to about 10 cm\(^3\) of D mixture. Repeat the test using distilled water in place D