NJC 2008 H2 CM prelim P1

Additional Materials: Multiple Choice Answer Sheet Data Booklet NATIONAL JUNIOR COLLEGE PRELIMINARY EXAMINATIONS 2008 CHEMISTRY 9258/01 Paper 1 Multiple Choice 10 September 2008 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name and index number on the an swer sheet in the spaces provided unless this has been done for you. There are forty 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 the wrong answer. Any rough working should be done in this booklet. You may use a calculator. This question paper consists of 16 printed pages (including this page). 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 Which of the following particles have more neutrons than protons and more electrons than neutrons? A NO2 + B 13CO3 2− C 32S2− D 14N2 + 2 Use of the Data Booklet is relevant to this question. Which one of the following has the most unpaired electrons? A the manganese ion in MnO2 B the ammonium ion in NH4Cl C the nickel metal D the nitride ion in AlN 3 Which of the following electronic configurations represent an element that forms a simple ion with a charge of -2? A 1s2 2s2 2p63s2 B 1s2 2s2 2p63s2 3p4 C 1s2 2s2 2p63s2 3p6 4s2 D 1s2 2s2 2p63s2 3p6 3d4 4s2 4 Which one of the following is planar? A CH3CH=CH2 B HNO3 C BCl4 − D H3O+ 2

5 Two bulbs R and S are connected to a 9 dm3 chamber as shown below. chamber (vacuum) Ar 3 dm3 Ne 4 dm3 PAr = 400 kPa PNe = 200 kPa R S What will be the total pressure in the vessel when the valves are opened at constant temperature? A 600 kPa B 286 kPa C 222 kPa D 125 kPa 6 When 0.20 moles of compound D were strongly heated with a Bunsen flame, 12 dm 3 of gas was collected at room temperature and pressure. Which one of the following compounds could D be? A MgCl2 B MgCO3 C Mg(NO3)2 D Mg(OH)2 7 Given the ΔH o and ΔSo of vapourization of liquid E are +10.0 kJ mol−1 and +37.6 J mol−1 K−1 respectively, the normal boiling point of liquid E is A 240 K B 266 K C 300 K D undeterminable from the data. 3

8 When propane burns in air, carbon dioxide and water will be formed. How many drops of water will be formed if 0.100 mol of carbon dioxide is produced? (Assume one drop of water has a volume of 0.05 cm3 and it contains 1.70 x 1021 water molecules) A 26.6 B 35.4 C 47.2 D 142 9 Which one of the following graphs shows the changes in pH when water is added to a sample of aqueous sodium hydroxide? A B CpH pH Volume of water 7 10 When the system H 2(g) + I2(g) 2HI(g) is in equilibrium at 444 oC, at 1 atm pressure, the value of the equilibrium constant, Kp, is 40. What is the value of Kp at a pressure of 2 atm at the same temperature? A 20 B 40 C 80 D 120 Volume of water 7 pH Volume of water 7 pH D Volume of water 7 4

11 The rate information below was obtained for the reaction P + Q → products. [P] / mol dm−3 [Q] / mol dm−3 Rate / mol dm−3 s−1 0.01 0.05 1.9 x 10−4 0.02 0.05 3.9 x 10−4 0.02 0.01 4.0 x 10−4 If the rate constant doubles for each 10 o C rise in temperature, which of the following sets of conditions will give the greatest rate of reaction? Temperature /oC [P] / mol dm−3 [Q] / mol dm−3 A 0.1 0.2 40 B 0.2 0.2 30 C 0.3 0.1 30 D 0.4 0.4 20 12 The graph shows the equilibrium percentage of ammonia present during the formation of ammonia by the Haber process: N 2(g) + 3H2(g) 2NH3(g) ΔHo = − 92 kJ mol−1 Which one of the following are correct labels for the graph? x axis % NH3 curve B curve A x axis curve A curve B A temperature high pressure low pressure B temperature low pressure high pressure C pressure high temperature low temperature D pressure low temperature high temperature 5

13 When a large current was passed through acidified aqueous copper(II) sulphate, there was simultaneous liberation, at the cathode, of x mol of copper and y dm3 of hydrogen (measured at r.t.p.)? How many moles of electrons were passed through the solution? A x + y/24 B 2x + y/12 C x + y/12 D 2x + y/24 14 All of the following about Period 3 elements and compounds are true except: A Atomic radius decreases across the Period. B Electronegativity increases across the Period. C The pH of the chlorides generally decreases across the Period. D Melting point of oxides decreases across the Period. 15 Both chlorine and bromine can oxidize iron(II) ions but not iodine. All the following may be reasons for the observations except: A the electronegativity of the halogens decreases down the group. B the oxidizing power of the halogens decreases down the group. C chlorine and bromine have a greater attraction for electrons than Fe 2+ has D the oxidising power of iodine is stronger than Fe3+. 16 When drops of aqueous ammonia are added to a solution of Cu(NO 3)2, a pale blue precipitate is formed. This precipitat e dissolved when excess aqueous ammonia is added, forming a deep blue solution. On addition of dilute hydrochloric acid, the pale blue precipitate is reformed. Which process does not occur in the above? A Dative bond formation B Formation of a complex ion. C Reduction of copper(II) ions. D Precipitation of copper(II) hydroxide. 6

17 Which one of the statements of the Group II elements (magnesium to barium) or their compounds is correct? A The stability of the carbonate to heat decreases on descending the group. B The magnitude of the enthalpy change of hydration of the metal ion increases on descending the group. C The most suitable method for extracting Group II elements is to reduce their oxides with carbon. D The lattice energy of the Group II sulphates is less exothermic on descending the group. 18 Compound H undergoes the following reactions: H C 4H8 C H 3COCH3 + CO2 ethanolic KOH KMnO4/H2SO4 Compound H could be A CH3CH2CH2CH2I B CH3CH2CHICH3 C CH3CHICHICH3 D (CH3)2CHCH2I 19 Which one of the following CANNOT be used to distinguish between the following compounds? OH C COCH3 CH3 HO A Hot acidified K2Cr2O7 B Neutral iron(III) chloride C Sodium carbonate D Silver diammine complex 7

20 Under identical conditions, reaction 1 proceeds faster than reaction 2 even though the mechanisms for both reactions are the same. reaction 1 CH 3CHBrCH3 + NaCN → CH3CH(CN)CH3 + NaBr reaction 2 CH 3CHBrCH3 + NaI → CH3CHICH3 + NaBr What factor will explain this result? A The C I bond is a stronger bond than the C Br bond. B The C N bond is a stronger bond than the C I bond. C The cyanide ion is a stronger nucleophile t