Consider the given trends in physical properties of elements in the Periodic Table: (i) Electron affinity increases from left to right. (ii) Densities increase down the group. (iii) Melting point of metals increases down the group. (iv) Metallic character increases from left to right. Which combination demonstrates correct trends?

Match the chemical equations in List A with the corresponding types of chemical reactions in List B by writing the letter of the correct response beside the item number in the answer booklet provided. List A (i) NH3(g) + HCl(g) NH4Cl(s) (ii) C(s) + O2(g) ’ CO2(g) + Heat (iii) 2C(s) + 2H2(g) + Heat ’ CH4(g) (iv) N2(g) + 3H2(g) ’ 2NH3(g) (v) H2SO4(aq) + 2KOH(aq) ’ K2SO4(s) + 2H2O(1) (vi) CaCO3(s) >CaO(s) + CO2(g) List B A Endothermic reaction B Ionic reaction C Exothermic reaction D Neutralization reaction E Reversible reaction F Homogeneous reaction G Displacement reaction H Decomposition reaction

1. NH3(g) + HCl(g) NH4Cl(s) (1 mk)
2. C(s) + O2(g) ’ CO2(g) + Heat (1 mk)
3. 2C(s) + 2H2(g) + Heat ’ CH4(g) (1 mk)
4. N2(g) + 3H2(g) ’ 2NH3(g) (1 mk)
5. H2SO4(aq) + 2KOH(aq) ’ K2SO4(s) + 2H2O(1) (1 mk)
6. CaCO3(s) >CaO(s) + CO2(g) (1 mk)

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To'ne as chematic diagram, illustrate the correct sequence of urban water treatment

1. Illustrate the correct sequence of urban water treatment using a schematic diagram. (5 mk)

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Briefly explain the importance of a laboratory coat, safety goggles, gloves and protective masks. as safety equipment in the Chemistry laboratory. (a) Jdentify the uses ol the giVen apparatuses: (b) Reagent botle (i) Filter funnel (ii) Page 4 of 6

1. Reagent bottle (1 mk)
2. Briefly explain the importance of a laboratory coat, safety goggles, gloves and protective masks as safety equipment in the Chemistry laboratory. (5 mk)
3. Filter funnel (1 mk)
4. Identify the uses of the given apparatuses: Mortar and pestle (1 mk)
5. Identify the uses of the given apparatuses: Bunsen burner (1 mk)

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Explain six scientific procedures used by scientists to investigate scientific problems.

1. Explain six scientific procedures used by scientists to investigate scientific problems. (6 mk)
2. Explain six scientific procedures used by scientists to investigate scientific problems. (0 mk)

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Justify each of the following statements. (i) It is advisable to use an evaporating dish instead of conical flask to evaporate a solution. (ii) In filtration process, the filtrate passes through the filter paper while the residue does not. (iii) Melting of ice is regarded as a physical change. (iv) Rusting of iron is regarded as a chemical change. (v) Carbon is a non-metal. (b) As olution of sugar is said to be a mixture. Justify the statement using four points.

1. Rusting of iron is regarded as a chemical change. (1 mk)
2. Carbon is a non-metal. (0 mk)
3. Carbon is a non-metal. (1 mk)
4. A solution of sugar is said to be a mixture. Justify the statement using four points. (0 mk)
5. A solution of sugar is said to be a mixture. Justify the statement using four points. (3 mk)

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Why is it not advisable to examine a car battery using a burning candle light. (ii) Why is the blue colour disappears during electrolysis of copper (II) sulphate solutions using carbon electrode? (iii) Why is a concentrated sulphuric acid not an electrolyte? (b) With the aid of ionic equations at the anode and cathode, explain the difference between the electrolysis of dilute NaCl using carbon electrode and molten NaCl.

1. Why is a concentrated sulphuric acid not an electrolyte? (0 mk)
2. Why is a concentrated sulphuric acid not an electrolyte? (2 mk)
3. With the aid of ionic equations at the anode and cathode, explain the difference between the electrolysis of dilute NaCl using carbon electrode and molten NaCl. (4 mk)
4. With the aid of ionic equations at the anode and cathode, explain the difference between the electrolysis of dilute NaCl using carbon electrode and molten NaCl. (0 mk)

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With examples, explain the given terms as used in chemistry: (i) Fire extinguisher (ii) Combustible material (b) Identify four stages of extinguishing fire using a carbon dioxide extinguisher. (c) Suggest the three components needed to start fire.

1. Explain the term 'Combustible material' with examples. (2 mk)
2. Combustible material (0 mk)
3. Identify four stages of extinguishing fire using a carbon dioxide extinguisher. (3 mk)
4. Identify four stages of extinguishing fire using a carbon dioxide extinguisher. (0 mk)
5. Suggest the three components needed to start fire. (2 mk)
6. Suggest the three components needed to start fire. (0 mk)

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You paid a visit to a certain village which has a scarcity of cooking fuel but plenty of raw materials for generating biogas. How would you advise the villagers with regard to the given aspects? (a) Nature of the gas. (b) Raw material for generating the gas. (c) The process involved in generating the gas. (d) Three advantages of using biogas over charcoal.

1. Nature of the gas. (0 mk)
2. Raw material for generating the gas. (0 mk)
3. The process involved in generating the gas. (0 mk)
4. Three advantages of using biogas over charcoal. (0 mk)

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Illustrate five environmental destructions caused by the process of extraction of metals and suggest five intervention measures to control the problem.

1. Illustrate five environmental destructions caused by the process of extraction of metals. (0 mk)
2. Suggest five intervention measures to control the problem. (0 mk)

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Using five points, explain the harmful effects of Terrestrial pollution.

1. Using five points, explain the harmful effects of Terrestrial pollution. (0 mk)

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