SAJC 2008 H2 Prelims P1

ST ANDREW’S JUNIOR COLLEGE JC2 Preliminary Examinations CHEMISTRY Higher 2 9746/01 Paper 1 Multiple Choice 11 September 2008 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, Centre number and candidate number on the Answer Sheet in the spaces provided unless this has been done for you. There are fourty questions on this paper. Answer all questions. For each question there are four possible answers A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. This document consists of 20 printed pages including this page.

Section A For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1. In an experiment, 15 cm3 of a hydrocarbon underwent complete combustion in 75 cm3 of oxygen. The final gaseous mixture contained 30 cm3 of carbon dioxide and 30 cm3 of unreacted oxygen. All gaseous volumes were measured under room temperature and pressure. What is the molecular formula of the hydrocarbon? A CH4 B C2H4 C C2H6 D C3H6 2. 50.0 cm3 of 0.0500 mol dm-3 KClO4(aq) requires 50.0 cm3 of 0.200 mol dm-3 TiCl3(aq) to reach end-point. Given that Ti(III) is oxidized to Ti(IV) in this reaction, what is the oxidation state of the reduced product of the ClO4 - ion? A -1 B +1 C +3 D +5 3. A flask L containing an unknown volume of neon gas at a pressure of 2 kPa was connected to a flask M containing 3 dm 3 of helium gas at 4 kPa. The final pressure in the connected flasks was found to be 3.5 kPa. What was the volume of flask L, assuming that the temperature was constant throughout? A 1.0 dm3 B 1.5 dm3 C 2.0 dm3 D 2.5 dm3 [Turn Over - 2 -

4. Particle Number of neutrons Number of nucleons Q- 16 33 R+ 19 39 S2- 17 33 T2+ 18 35 Which of the following pairs consists of particles that are isoelectronic? A Q- and S2- B R+ and S2- C S2- and T2+ D Q- and T2+ 5. An element X has the electronic configuration [Kr] 4d 10 5s2 5p3. What is the likely formula for the fluoride of X? A X3F B XF2 C XF5 D XF6 6. Which of the following ions will be deflected the most when passed through an electric field? A +Na23 11 B −2 16 8 O C +2 24 12 Mg D −Cl35 17 [Turn Over - 3 -

7. Which of the following molecules is linear? A Cl-S-Cl B O=N-Br C H-O-O-H D O=C=C=C=O 8. Which of the following sets of compounds all contain the same type of forces of attraction between molecules of their own? A CO2, NO2, SO2 B NaCl, MgCl2, AlCl3 C BF3, CH4, SF6 D AgCl, I2, SiO2 9. The heat changes of the corresponding reactions are given as follows: C(s) + 2 1 O2(g) → CO(g) ΔHo = -110 kJ mol-1 2Cr(s) + 2 3 O2(g) → Cr2O3(s) ΔHo = -1120 kJ mol-1 What is the enthalpy change for the following reaction? 3C(s) + Cr2O3(s) → 2Cr(s) + 3CO(g) A +590 kJ mol-1 B +790 kJ mol-1 C -870 kJ mol-1 D -940 kJ mol-1 [Turn Over - 4 -

10. Phosphorus can react with chlorine to form phosphorus pentachloride and phosphorus trichloride. Some thermochemical data related to these compounds are shown below: Enthalpy change of atomisation of phosphorus +315 kJ mol-1 Enthalpy change of atomisation of chlorine +122 kJ mol-1 Enthalpy change of formation of PCl5 -440 kJ mol-1 What is the bond energy for the P–Cl bond in PCl5? A 273 kJ mol-1 B 485 kJ mol-1 C 925 kJ mol-1 D 1365 kJ mol-1 11. The decomposition of compound W is shown below. W (g) Æ Y(g) + Z(g) The rate equation for the decomposition is found to be: rate = k[ W] where rate constant, k = 0.45 s-1. What is the time taken for W(g) to reach one third of its initial concentration of 1.8 mol dm-3? A 1.54 s B 2.44 s C 2.98 s D 3.08 s [Turn Over - 5 -

12. Hydrogen peroxide reacts with acidified iodide ions liberating iodine according to the equation below: H 2O2 (aq) + 2H+ (aq) + 2I- (aq) Æ I2 (aq) + 2H2O (l) The kinetics of this reaction were investigated and it was found to have the following rate equation: rate = k [H 2O2] [I-] Two series of experiments were conducted giving rise to Graph A and Graph B. Graph A Graph B rate of reaction/ mol dm-3 s-1 y x time Which of the following shows the correct labeling of the x-axis for Graph A and y-axis for Graph B? x-axis for Graph A y-axis for Graph B A [H2O2] [I-] / mol2 dm-6 [H +] / mol dm-3 B [I-] [H+] / mol2 dm-6 [ I2] / mol dm-3 C [H2O2] / mol dm-3 [I-] / mol dm-3 D [H+] / mol dm-3 [H 2O2] / mol dm-3 13. Chlorine dioxide, ClO2, is a yellow gas which can be synthesised in the laboratory by the following reaction: 2AgClO3(s) + Cl2(g) 2AgCl(s) + 2ClO2(g) + O2(g) ∆H = 0 Which of the following statements is incorrect about the above reaction? A The addition of a catalyst will increase the rates of both the forward and the reverse reactions. B The equilibrium constant is dependent on temperature. C The rate constants vary with temperature. D Increasing the pressure decreases the equilibrium yield of ClO 2. [Turn Over - 6 -

14. What is the final pH of the solution formed by mixing equal volumes of two separate solutions of pH 1.0 and pH 2.0? A 0.66 B 0.96 C 1.26 D 1.56 15. The table below contains the standard reduction potential data for the species of copper and mercury. E o / V Cu2+(aq) + e Cu+(aq) +0.15 Cu+(aq) + e Cu(s) +0.52 Hg2+ (aq) + e Hg+(aq) +0.91 Hg+(aq) + e Hg(l) +0.80 Using the data, which of the following can be predicted? A Neither Cu+ nor Hg+ undergoes disproportionation. B Only Cu+ undergoes disproportionation. C Only Hg+ undergoes disproportionation. D Both Cu+ and Hg+ undergo disproportionation. [Turn Over - 7 -

16. Three electrochemical cells are set up as shown below. The e.m.f in volts is shown below for each cell. From these e.m.f. values, what is the order of reducing power? Most Least A Y W Z X B Y X W Z C Z X Y W D Z X W Y 17. Compounds of Period 3 elements dissolve in water to form aqueous solutions that are acidic, basic or neutral. Which of the following sequence shows the order of increasing pH of the resultant solutions formed when the compounds are dissolved in water? A NaCl, MgCl 2, SiCl4 B AlCl3, SiCl4, PCl5 C Al2O3, MgO, SO2 D P4O10, SiO2, MgO [Turn Over e.m.f. = 0.76 V X Salt bridge 0.5 mol dm-3 W2+(aq) e 0.5 mol dm- V W 3 X2+(aq) e.m.f. = 0.87 V Z Salt bridge 0.5 mol dm-3 X2+(aq) X e 0.5 mol dm-3 Z2+(aq) e.m.f. = 0.35 V X Salt bridge 0.5 mol dm-3 Y2+(aq) Y e 0.5 mol dm-3 X2+(aq) V V - 8 -

18. On descending Group II elements from magnesium to barium, which statement about the trend in properties is incorrect? A The reducing power of the elements increase down the group. B The thermal stability of the nitrates increases. C The magnitude of the lattice energy of the oxides increases. D The ionic radii increases. 19. Which ions containing chlorine are formed when chlorine is bubbled in hot aqueous sodium hydroxide? A Cl- and ClO- B Cl- and ClO3 - C Cl- and ClO4 - D ClO- and ClO3 - 20. Whi