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No expanded working has been attached for this question yet. The verified answer is Option A.

No expanded working has been attached for this question yet. The verified answer is Option B.

(a) Burette reading Rough titration (cm\(^3\)) 1st titration (cm\(^3\)) 2nd titration (cm\(^3\)) Final Burette reading 21.50 37.10 22.60 Initial Burette reading 06.00 21.50 07.10 15.50 15.60 15.50 Average titre = \(\frac{15.50 + 15.60 + 15.50}{3}\) = 15.53 cm\(^3\) (b)(i) Concentration of B in moldm\(^{-3}\) H\(_2\)SO\(_4\) + 2XOH \(\to\) X\(_2\)SO\(_4\) + 2H\(_2\)O \(\frac{C_AV_A}{C_BV_B}\) = \(\frac{1}{2}\) C\(_B\) = \(\frac{C_AV_A \times 2}{V_B}\) = \(\frac{0.05 \times 15.53 \times 2}{25}\) = 0.0621 moldm\(^{-3}\) (ii) Molar mass of XOH Conc. B in g/dm\(^3\) = \(\frac{1.4 \times 1000}{250}\) = 5.6 g/dm\(^3\) Molar mass of XOH = \(\frac{5.6 g/dm^3}{0.0621 mol/dm^3}\) = 9.2 g/mol Sample C is Fe(NH\(_4\))\(_2\) (SO\(_4\))\(_2\) (ii) Relative atomic mass of X XOH = 90.2 X + 16 + 1 = 90.2 X = 90.2 - 17 = 73.2

(a)(i) The common name given to group VII elements is Halogens. (ii) Hydrides of the first two elements in group VII: (1) Hydrogen fluoride (2) Hydrogen chloride. (iii) Three chemical properties of group VII elements are: (1) High electron affinity/strong oxidation 4-gents/electron acceptor. (2) High electronegative (3) React with hydrogen to form acid. (4) Form salts with metals. (5) React with alkalis to form salts. (6) React with water to form acids. (7) Displacement of lower halogens from their acids/salts. (8) Reacts with hydrocarbons to form alkyl halids. (b) Copy and complete the following table: Particles Number of Neutrons Number of electrons Number of prontons Mass Number W\(^{2+}\) 12 10 12 24 X\(^{2+}\) 8 10 8 16 Y 14 13 13 27 Z 12 11 11 23 (c)(i) Define the following processes: I. Nuclear fission – splitting of a heavy nucleus into smaller nuclei (of smaller mass) with release of (large amount of) energy and radiations. II. Nuclear fusion –combination of smaller nuclei to form a large nucleus with the release of (large amount of) energy and radiation. (ii) Give one use of each process in (c)(I). I. Used to generate electricity/nuclear or hydrogen bomb/ production of new elements/production of radioisotopes. II. Used to produce nuclear weapon/ atomic or hydrogen bomb/production of new elements/production of radioisotopes. (c)(i) List three types of radiation that are produced during radioactivity: (1) alpha (2) beta (3) gamma. (d)(ii) Arrange the radiation listed in (d)(i) in order of increasing: I. Penetrating power — \(\alpha\), < \(\beta\) < \(\gamma\) II. Ionizing power — \(\gamma\) < \(\beta\) < \(\alpha\)

(a)(i) Define each of the following terms: I. Normal salt: Salt formed when all the replaceable hydrogen ions/replaceable hydrogen atoms of an acid are replaced by a metal/ammonium ion. Or a salt formed when all the OH\(^-\) of the alkali are replaced by an ionic group of an acid. II. Acid salt: Salt formed when only some part of the (replaceable) hydrogen ions/atoms of an acid are replace a metal. (ii) Tetraoxosulphate VI acid and sodium hydroxide react to produce s d water. Write a balanced chemical equation for the formation of: I. A normal salt: 2NaOH + H\(_2\)SO\(_4\) \(\to\) Na\(_2\)SO\(_4\) + 2H\(_2\)O. II. An acid salt: NaOH + H\(_2\)SO\(_4\) \(\to\) NaHSO\(_4\) + H\(_2\)O. (b)(i) Explain briefly the term acid-base indicator: It is either a weak acid or weak base which gives different colour in acid alkaline medium/depending on pH of the solution. (ii) Copy and complete the following table: (ii) Copy and complete the following table. Indicator , Colour in acidic medium , Colour in basic medium Methyl orange Red/Pink Yellow Phenolphthalein Colourless Pink/Red (iii) For each of the following titrations, state the most suitable indicator:- I. Strong acid against strong base – Methyl orange/methyl red/litmus/bromocresol blue or red. II. Strong acid against weak base – Methyl orange. III. Weak acid against strong base – Phenolphthalein. (c) Baking soda and hydrochloric acid react according to the following equation: NaHCO\(_{3(aq)}\) + HCl\(_{(aq)}\) \(\to\) NaCl\(_{aq}\) + CO\(_{2(aq)}\) + H\(_2\)O Calculate the mass of baking soda that would produce 10g of carbon(iv)oxide. [ H = 1, C = 12, O = 16, Na = 23 ] Relative molar mass (CO\(_2\)) = 12 + (2 x 16) = 44. Relative molar mass (NaHCO\(_3\)) = 23 + 1 + 12 + (3 x 16) = 84

(a)(i) Define the term standard electrode potential: It is the measure of the tendency of an element to form ions in solution relative-to the tendency of hydrogen atoms to form ions in solution at standard condition/ the potential difference that exists between an electrode and the hydrogen electrode under standard conditions (of I moldm\(^{-3}\) concentration at 298k and 1 atm). (ii) State three factors that affect the discharge of ions during electrolysis: (1) Position of ions in the electrochemical series/standard electrode potential value. (2) Nature or reactivity of electrode used. (3) (relative) concentration of ions. (iii) State two functions of a salt. bridge in an electrochemical cell: (1) Allows electrical contact between two solutions/complete the electric circuit (2) Maintains electrical neutrality in each half cell/allows ions flow in and out of salt bridge. (b)(i) Describe briefly what happens when a solution of copper(II) tetraoxosulpahte(VI) is electrolysed using copper electrodes: CuSO\(_4\) \(\rightleftharpoons\) Cu\(^{2+}\) + SO\(_4^{2-}\); Cu\(^{2+}\) discharged/Cu metal deposited/Cu cathode increases in mass. H\(_2\)O \(\rightleftharpoons\) H\(+\) + OH\(-\) Copper anode dissolves/ionizes/decreases in size to give Cu\(^{2+}\) ions. Solution remains blue/concentration of Cu\(^{2+}\) ions is constant. (c) Calculate the mass of copper(II)tetraoxosulphate(V1) for 35 minutes using copper electrodes:. [H=1, O=16, S=32, Cu=64, IF=96,500] Cu\(^{2+}\) + 2e ---> Cu Q = It = 0.2 x 35 x 60 = 420C 2F = 2e = 1mole \(\frac{Cu}{2}\) x 96500C = 64g 420C = \(\frac{420}{ 2 x 96500}\) x 64gCu = 0.14gCu. (d)(i) State three characteristics of catalyst: (1) Remains unchanged in chemical nature and mass. (2) Does not affect the types of product formed. (3) Alters (increase or decrease) the rate of chemical reaction. (4) They are reactions specific. (5) Cannot initiate a reaction that is not feasible. (6) Has no effect on the equilibrium of a reversible reaction. (7) Required in small quantity. (ii) Name one manufacturing process in which each of the following metals is used as a catalyst: I. Iron – used in Haber process. II. Nickel – hydrogenation of vegetable oil/alkenes. III. Platinum – used in preparation of hydrogen iodido from hydrogen and iodine/contact process for H\(_2\)SO\(_4\) production/manufacture of HNO\(_3\) used in Hydrogenation.

(a)(i) Define the term Hygroscopic: Hygroscopic substance – is defined as a substance which absorbs moisture on exposure to the atmosphere but does not form solution or change state. (ii) Give two differences between a physical and a chemical change: Physical Change Chemical Change No new substance formed New substance formed Change is easily reversibl Change is not easily reversible Heat change is not usually involved Heat is usually given out or absorbed/it involves heat No change in mass of substance involved Change in mass of substance involved (iii) Using the kinetic theory of gases, explain briefly the Charles' law: At constant pressure, when the temperature of a gas is increased, the molecules gain more kinetic energy and move faster. The distance between the molecule increases resulting in increased in the volume of the gas. (b)(i) Arrange the following compounds in order of increasing boiling points: CO\(_2\), CS\(_2\), NaH CO\(_2\) — Weak vander Waal's forces. CS\(_2\) — Stronger vander Waals's forces. NaH — With ionic forces stronger than vander Waal's forces. (ii) Write a balanced equation to illustrate the reaction of chlorine gas with cold dilute sodium hydroxide. Cl\(_{2(g)}\) + 2NaOH\(_{(aq)}\) \(\to\) NaCl\(_{(aq)}\) ; NaCI\(_{(g)}\) + H\(_2\)O\(_{(l)}\) (c) In a certain reaction, 15.0g of impure magnesium sample reacted with excess hydrochloric acid liberating 8.6dm\(^3\) of hydrogen gas at s.t.p (I) Write a balance equation for the reaction. Mg\(_{(g)}\) 2HCI\(_{(aq)}\) ---> MgCl\(_{2(ag)}\) + H\(_{2(g)}\). (ii) Calculate the: I. Mass of pure magnesium in the sample Mg + 2HCI \(\to\) MgCl\(_2\) + H\(_2\) 1 mole H\(_2\) = 1 moles mg n(H\(_2\)) = \(\frac{8.6}{ 22.4}\) = 0.384moles. Hence, number of moles of Mg = 0.384moles Mass of Mg = mole x molar mass = 0.384 x 24 = 9.21g. II. % purity = \(\frac{\text{Mass of pure Mg}}{\text{Mass of impure Mg}}\) x 100 Mg = \(\frac{9.21}{15.0}\) x 100 = 61.4% Ill. From the equation; Moles of cl\(^{-2}\) = 2 x moles of Mg = 2 x 0.384 = 0.768 moles No of Cl\(^{-}\) produced x N\(_A\) = 0.768 x 6.02 x 10\(^{23}\) = 4.62 x 10\(^{23}\) Cl\(^{-}\)

(a)(i) Explain briefly the term chemical industry: It is an industry which uses chemical processes convert raw materials into useful products. (ii) State 3 factors that should be considered in sitin chemical industry. (1) Availability of resources needed. (2) Good communication skills. (3) Nearn to markets. (4) Availability of labour. (5) Availability of space. (6) Good climate condition. (7) Favourable transport system (8) Nearness to source of energy. (9) Nearness to raw materials (10) Government policy. (b)(i) Describe how tin is extracted from its ore: The ore is crushed into powder, washed with water and filtered to remove impurities/concentration of ore. The ore is roasted in air to remove impurities. roasted is mixed with coke/charcoal and heated in a furnace/high temperature/1300^\circC where it is reduced to tin/C + SnO\(_2\) ---> Sn + O\(_2\). Limestone is added to remove earthly impurities as slag/CaCO\(_2\) + SiO\(_3\) ---> CaSiO\(_3\) + CO\(_2\) Molten tin is tapped off. (ii) It is used to coat iron or steel (as a protection aga corrosion). It is used in making alloys (e.g. Bronze, type metal, solder). (c)(i) Name the constituents of cement: Calcium oxide/Calcium trioxocarbonate(IV), Silicon(IV) oxide and Aluminium oxide. (ii) How does mortar set? Mortor is a mixture of sand, cements/lime and WE When mortar is placed between two blocks it absorbs CO\(_2\) from the atmosphere to form CaCO\(_3\) with m given out. (d)(i).Explain briefly the term pollution: Pollution – introduction of harmful substance the environment/contamination of environment. (ii) Give two examples of air pollutants: Gases hydrocarbon, e.g. methane (CH\(_4\)), CO, NO\(_2\), SO\(_2\), NO, CFC's, oxides of lead, particuate matter, e.g. d pollen grains, soot, smoke and smog. (e)(i) Consider the following reversible reaction wh occurred at the temperature of 298k: N\(_{2(g)}\) + 3H\(_{2(g)}\) \(\rightleftharpoons\) 2NH\(_{3(g)}\); \(\Delta\)H = –92.37KJ. List two factors that would increase the yield of NH\(_{3(g)}\) — (1) Increase in pressure of the system/decrease in volume of system. (2) Decrease in temperature of tho system. (3) Removal of ammonia/products.

(a)(i) List two characteristics of a homologous series: (1) They can be represented by a gener molecular formula. (2) They have similar chemical properties. (3) They have same functional group (4) They can be prepared by a general method. (5) Each consecutive member differ by – CH\(_2\) group (6) Increase intensity of physical properties with increase in molar mass. (ii) Consider the compound represented by the following formula: CH\(_3\)(CH\(_2\))2CH\(_3\) I. Which homologous series does the compound belong? Ans: Alkanes II. Write the structures of 3 possible iscmers of the compound. (b) Write the structure of the major product forn I in each of the following reactions: (i) Ethanol with excess acidified KMnO\(_4\) (ii) Excess ethane with chlorine in the presence of sunlight. (iii) Ethanol with propanoic acid in the presence of few drops of concentrated tetraoxosulphate(VI)acid. (c) Name the major product in each reaction in (b): (i) Ethanoic acid. (ii) Chloroethane. (iii) Ethylpropanoate. (d) Consider the following organic compounds: X — (CH\(_3\))\(_3\)COH (i) Give the IUPAC name of each compound. X is 2-methylpropan-2-ol. Y is phenylmethanoic acid/benzoic acid. (ii) State a chemical test for the functional group in each compound. To sample X add some PCl\(_5\). Steaming white fumes of HCI will be observed. OR Add an organic acid to sample X and few drops of concentrated H\(_2\)SO\(_4\) or dry HCI gas and heat. A pleasant/fragrance/fruity smell is produced, confirms — OH in X. OR Add (saturated solution) of NaHCO\(_3\)/Na\(_2\)CO\(_3\) to sample Y. Effervescence of colourless, odourless gas which turns lime water milky. OR To sample Y, add an alkanol in the presence of conc. H\(_2\)SO\(_4\) or dry HCI. A pleasant/fragrance/fruity smell is produced, confirms — COOH in Y. (e)(i) moles = C; \(\frac{70.57}{12}\) H; \(\frac{5.90}{1}\) O; \(\frac{23.53}{16}\) moles = C; \(\frac{5.88}{1.471}\) H; \(\frac{5.90}{1.471}\) O; \(\frac{1.471}{1.471}\) emperica formula = C\(_4\)H\(_4\)O (ii) (C\(_4\)H\(_4\)O)n = 136 68n = 136 n = \(\frac{136}{68}\) n = 2 molecular formula - C\(_8\)H\(_8\)O\(_2\)

a)i) How would an aqueous solution of iron (II) tetraoxosulphate (VI) be converted into an aqueous solution of magnesium tetraoxosulpiiate (VI): Add magnesium ribbon/powder to the iron (II) 1tetraoxosulphate (vi) solution and stir. ii) Write a balanced equation for the reaction in (a)(i) above: Mg\(_{(s)}\) +FeSO\(_{4(aq)}\) \(\to\) MgSO\(_{4(aq)}\) + Fe\(_{(s)}\) (b) (I) Why are some compounds recrystallized after preparation? To make the compound pure/purify the compound/purification/to remove impurities because the compound is impure. (ii) Outline the steps in recrystallization: (1) Put the solid in a beaker and add appropriate/suitable solvent. (2) Heat the mixture to dissolve the solid. (3) Filter the hot mixture/solution. (4) Concentrate the filter. (5) Cool the filtrate for crystals to form. (6) Filter the crystals off; wash with some cold water and dry crystals in an oven (c)(i) Name two gases that can cause colour changes in an acidified solution of potassium heptaoxodichromate (VI): Sulphur(IV)oxide, hydrogen sulphide, ethene, ethyne, propene, propyne, butene, butyne. (ii) State the colour change expected in (c)(i) above; Potassium heptaoxodichromate (IV) turns from orange/yellow to green

TEST OBSERVATION INFERENCE (a) C\(_{(s)}\) + H\(_2\)O C dissolved to form a light green solution The solution turned blue litmus paper red C is a soluble salt Solution is acidic (b) C\(_{(aq)}\) + NaOH\(_{aq}\) in drop-wise In excess then heat Keeping for some minutes Green precipitate formed Precipitate insoluble in excess A choking/pungent/irritating (colourless) gas evolved which turns litmus paper blue/forms dense white fumes with conc.HCl The precipitate turned brown (at the upper part of the tube) Fe\(^{2+}\) present NH\(_3\) gas from NH\(_4^+\) Fe\(^{2+}\) oxidized to Fe\(^{3+}\) (c) C\(_{(aq)}\) + BaCl\(_{2(aq)}\) + HCl\(_{(aq)}\) White precipitate formed Precipitate undissolved SO\(_4^{2-}\) or SO\(_3^{2-}\) or CO\(_3^{2-}\) SO\(_4^{2-}\)

(a) Burette reading Rough titration (cm\(^3\)) 1st titration (cm\(^3\)) 2nd titration (cm\(^3\)) Final Burette reading 21.50 37.10 22.60 Initial Burette reading 06.00 21.50 07.10 15.50 15.60 15.50 Average titre = \(\frac{15.50 + 15.60 + 15.50}{3}\) = 15.53 cm\(^3\) (b)(i) Concentration of B in moldm\(^{-3}\) H\(_2\)SO\(_4\) + 2XOH \(\to\) X\(_2\)SO\(_4\) + 2H\(_2\)O \(\frac{C_AV_A}{C_BV_B}\) = \(\frac{1}{2}\) C\(_B\) = \(\frac{C_AV_A \times 2}{V_B}\) = \(\frac{0.05 \times 15.53 \times 2}{25}\) = 0.0621 moldm\(^{-3}\) (ii) Molar mass of XOH Conc. B in g/dm\(^3\) = \(\frac{1.4 \times 1000}{250}\) = 5.6 g/dm\(^3\) Molar mass of XOH = \(\frac{5.6 g/dm^3}{0.0621 mol/dm^3}\) = 9.2 g/mol Sample C is Fe(NH\(_4\))\(_2\) (SO\(_4\))\(_2\) (ii) Relative atomic mass of X XOH = 90.2 X + 16 + 1 = 90.2 X = 90.2 - 17 = 73.2

The ground state of an electron, the energy level it normally occupies, is the state of lowest energy for that electron.

General Gas Equation: \(\frac{P_1 V_1}{T_1}\) = \(\frac{P_2 V_2}{T_2}\) where P\(_1\) = 765 - 5 = 760mmhg \(V_2 = \frac{P_1 V_1 T_2}{P_2 T_1}\) \(V_2 = \frac{760 * 50 * 273}{ 760 * 283}\) → 48.23cm\(^3\)

: To remove oil paints, the use of chemicals is usually required, including turpentine, acetone, kerosene, and various paint thinners.