RJC Chemistry H1 P1 with Ans Prelim

RAFFLES JUNIOR COLLEGE PRELIMINARY EXAMINATION 2008 HIGHER 1 CHEMISTRY 8872/01 Paper 1 Multiple Choice 19 September 2008 50 minutes Additional Materials: Mult iple Choice answer sheet Data Booklet READ THESE INSTRUCTIONS FIRST DO NOT open this question booklet until you are told to do so. Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, Candidate Number on the Answer Sheet in the spaces provided. There are thirty 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 to be correct and record your choice with a soft pencil on the separate Answer Sheet. Read the instructions on the Answer Sheet very carefully. Each correct answer will score one mark. A ma rk will not be deducted for a wrong answer. Any rough working should be done in this booklet. This question booklet consists of 9 printed pages. -1-

Section A For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 An aqueous solution c ontaining 1 mole of S 2O3 2− ions reduces 4 moles of bromine molecules. What is the sulphur-containing product of this reaction? A H2S B SO2 C SO4 2− D S4O6 2− 2 The use of the Data Booklet is relevant to this question. The pH of pure water is 7.0 at 298 K. Whic h of the following quantities is equal to the number of ions in 1 dm3 of pure water at 298 K? A The number of neutrons in 8.0 x 10 –7 g of deuterium gas, D2 (D = 2H). B The number of atoms in 4.48 x 10–6 dm3 of Cl2 at s.t.p. C The number of molecules in 1.44 x 10–4 g of Buckministerfullerene, C60. D The number of anions in 1.0 x10–14 dm3 of 1.0 mol dm–3 K2C2O4(aq). 3 Self-igniting flares contain Mg 3P2. With water, this produces diphosphane, P2H4, which is spontaneously flammable in air. Which equation that includes the formation of diphosphane is balanced? A Mg 3P2 + 6H2O ⎯→ 3Mg(OH)2 + P2H4 B Mg 3P2 + 6H2O ⎯→ 3Mg(OH)2 + P2H4 + H2 C 2Mg 3P2 + 12H2O ⎯→ 6Mg(OH)2 + P2H4 + 2PH3 D 2Mg 3P2 + 12H2O ⎯→ 6Mg(OH)2 + 3P2H4 4 The table below contains incomp lete information about the two ions X and Y. Ion Mass number Atomic number Number of neutrons Number of electrons Charge of ion X 59 27 p q +2 Y 79 r 45 36 s Which of the following s hows the missing numbers (p, q, r and s) in the table above? p q r s A 29 27 34 +2 B 32 27 34 –2 C 59 25 36 +2 D 32 25 34 –2 -2-

5 An element Z has a second ionisation energy hi gher than that of the element preceding it and the element after it in the Periodic Table. What is the atomic number of Z? A 10 B 13 C 14 D 15 6 Which of the following solids consists of par ticles held together only by van der Waals’ forces? A NaCl B H2O C Cu D Ar 7 Which of the following is a non–polar molecule? A C 6H5Cl C CCl4 B CH 2F2 D CO 8 C 2H4 and C 2H2 are unsaturated hydrocarbons. Which of the following statements is CORRECT regarding these two molecules? A Both C 2H4 and C2H2 have the same shape. B C 2H4 has more σ bonds but fewer π bonds than C2H2. C The carbons in C 2H4 and C2H2 are sp and sp2 hybridised respectively. D The carbon–carbon–hydrogen bond angle is larger in C2H4 than in C2H2. 9 The use of the Data Booklet is relevant to this question. Consider the energy cycle given below. (g) + 3H 2(g) (g) (l)+ 3H2(g)(l) y kJ mol-1 x kJ mol-1 ΔHo What is the standard enthalpy change of hydrogenation of benzene, ΔHo, in kJ mol–1? A x – y –132 B x – y –372 C y – x –132 D y – x –372 -3-

10 Which one of the following best explains wh y the lattice energy of magnesium chloride is much more exothermic than that of lithium chloride? A Magnesium has a greater el ectronegativity than lithium. B Magnesium ions have a greater charge than lithium ions. C Magnesium ions have a greater i onic radius than lithium ions. D Magnesium ions have a greater pol arising power than lithium ions. 11 A chemical plant illegally dumped some r adioactive waste in a landfill. This waste composed of two radioactive isotopes M and N in the proportion 4:1. The decay of radioactive isotopes follows first- order kinetics. The half-life of M is 2 days whereas that of N is 4 days. By the time the authorities found out about this illegal dumping and analysed a sample of the waste, they found equal amounts of M and N. How long was the waste in the landfill before the authorities arrived? A 2 days B 4 days C 8 days D 16 days 12 The following reaction is first order with respect to G and zero order with respect to H. G + H ⎯→ products If the rate constant doubles for each 10 oC rise in temperature, which of the following sets of conditions will give the greatest rate of reaction? [ G]/mol dm-3 [ H]/mol dm-3 temperature/oC A 0.30 0.30 35 B 0.15 0.30 45 C 0.45 0.15 25 D 0.60 0.15 35 13 Which statement concerning the equilibrium reaction given below is correct? 2CrO 4 2–(aq) + 2H+(aq) Cr2O7 2–(aq) + H2O(l) A A redox reaction is taking place. B The equilibrium constant, Kc, has no units. C A decrease in pH will result in an increase in the concentration of Cr 2O7 2–(aq). D The addition of a catalyst will result in an increase in the concentration of Cr2O7 2–(aq). -4-

14 The graphs below show the variation of the percentage of gaseous products present at equlibrium, with temperature and pressure. % products at equilibrium (T + 10) oC T oC Pressure Which one of the following systems could the graphs represent? A N 2(g) + 3H2(g) 2NH3(g) ΔH = –92 kJ mol–1 B 3O 2(g) + 4NH3(g) 2N2(g) + 6H2O(g) ΔH = –1248 kJ mol–1 C 2N 2(g) + O2(g) 2N2O (g) ΔH = +82 kJ mol–1 D CO2(g) + C(s) 2CO (g) ΔH = +173 kJ mol–1 15 Which one of the following pairs will give a buffer solution when equal volumes of the two solutions are mixed? A 0.1 mol dm–3 NaOH and 0.1 mol dm–3 CH3COOH B 0.2 mol dm –3 Ba(OH)2 and 0.1 mol dm–3 H2C2O4 C 0.05 mol dm–3 Ba(OH)2 and 0.2 mol dm–3 CH3COOH D 0.2 mol dm –3 NaOH and 0.1 mol dm–3 H2C2O4 16 Which property when plotted against increasing atomic number gives the shape of the following graph? atomic number A Boiling point of F 2, Cl2, Br2 and I2 B First ionisation energy of Mg, Ca, Sr and Ba C Atomic radius of Na, Mg, A l and Si D Electronegativity of F, C l, Br and I -5-

17 Which of the following ions has the largest ionic radius? A N3− B F− C Na+ D Mg2+ 18 How many isomers of molecular formula C9H12 contain a benzene ring? A 6 B 7 C 8 D 9 19 Which one of the following structures will have cis-trans isomers? A CH 3BrC=CCl2 C CH 2=CH–CH2–CH=CH2 B D C 6H5CH=CHCOOH 20 Iron filings were added to a solution cont aining equimolar quantities of methylbenzene and bromine. The mixture was immediately placed in the dark until no further change took place. Which of the following are likely to have been the main products? A C B D and Br CH3 CHBr2 and CH2Br CHBr2 and CH2Br Br Br CH2Br and Br CH3 Br CH3 -6-

21 In the preparation of ethene, ethanol is added a drop at a time to a heated reagent Y. The impure ethene is washed by being bubbled through a solution Z and then collected. What