2012 JJC H1 Prelim P1

JURONG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 1 CHEMISTRY 8872/01 Paper 1 Multiple Choice 13 September 2012 50 minutes 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, class and shade your exam index number on the Answer Sheet in the spaces provided. There are thirty questions on this pape r. 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. A Data Booklet is provided. Do not write anything on the Data Booklet. This document consists of 11 printed pages and 1 blank page. [Turn over

2 Jurong Junior College 8872/01/Prelim 2012 [Turn Over SECTION A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1. 0.200 mol of a hydrocarbon undergo complete combustion to give 35.2 g of carbon dioxide and 14.4 g of water as the only products. What is the molecular formula of the hydrocarbon? A C2H4 B C2H6 C C4H4 D C4H8 2. A giant molecule contains a mixture of two carbon isotopes, 12C and 13C. It was found that the relative atomic mass of carbon in the molecule is 12.20. What is the ratio of 12C to 13C in the molecule? A 5:4 B 4:1 C 4:5 D 1:4 3. The use of Data Booklet is relevant to this question. In research on the atomic nucleus, scientists have been comparing the stability of isotopes with the same neutron : proton ratio. Which isotope has the same neutron : proton ratio as 10B? A 32P B 40Ar C 32S D 40K 4. Which element has an equal number of electron pairs a nd of unpaired electrons in the orbitals of principal quantum number 2? A beryllium B carbon C nitrogen D oxygen

3 Jurong Junior College 8872/01/Prelim 2012 [Turn Over 5. A plasma is a gaseous mixture in which the atoms have been completely stripped of their electrons, leaving bare nuclei. Due to possible use in controlled nuclear fusion reactions, plasma behavior has been intensively studied. When passed between two elect rically charged plates, 1H and 4He nuclei are deflected differently. The deflection path of 1H is shown in the diagram below. Which of the following is correct? Polarity of Plate direction of deflection of 4He angle of deflection of 4He X Y A – + towards Y 0.5 ° B + – towards Y 1 ° C – + towards X 1 ° D + – towards X 0.5 ° 6. An ion IF4n− has a square planar shape as shown below. What is the value of n? A 1 B 2 C 3 D 4 I F F F F 2 o 1H Source X Y

4 Jurong Junior College 8872/01/Prelim 2012 [Turn Over 7. Methyl isocyanate, CH3NCO, is a toxic liquid which is used in the manufacture of some pesticides. The sequence of atoms in the methyl isocyanate molecule is H3C−N=C=O. What is the correct increasing order of bond angles α, β and γ in the molecule shown below? A γ < β < α B β < α < γ C α < β < γ D α < γ < β 8. Three elements, E, F and G, have the physical properties shown in the table. element melting point / oC boiling point / oC density / g cm−3 E F G −7 98 649 59 883 1107 3.12 0.97 1.74 What could be the identities of E, F and G? E F G A B C D Br2 Br2 I2 I2 Al Na Mg Si Si Mg Na K 9. Which of the following correctly describes the effect of pressure change on the following equilibrium? N2(g) + 3H2(g) ⇌ 2NH3(g) Pressure Proportion of N2 and H2 Effect on equilibrium constant A increases increases no change B increases decreases no change C decreases increases decreases D decreases decreases increases γ α β

5 Jurong Junior College 8872/01/Prelim 2012 [Turn Over 10. The standard enthalpy change for two reactions are given by the equations: 2Fe(s) + 3 2 O2(g) → Fe2O3(s) H = −822 kJ mol−1 C(s) + 1 2 O2(g) → CO(g) H = −110 kJ mol−1 What is the standard enthalpy change for the following reaction? Fe2O3(s) + 3C(s) → 2Fe(s) + 3CO(g) A −712 kJ mol−1 B −492 kJ mol−1 C +712 kJ mol−1 D +492 kJ mol−1 11. Which of the following is not a conjugate acid-base pair? A NH3+CH2CO2− and NH2CH2CO2− B OH− and O2− C HPO42− and H2PO4− D H2SO4 and SO42− 12. Which sequence shows the compounds in order of decreasing pKa values? A CH3CO2H > C2H5OH > CF3CO2H > CCl3CO2H B CF3CO2H > CCl3CO2H > CH3CO2H > C2H5OH C C2H5OH > CH3CO2H > CCl3CO2H > CF3CO2H D CCl3CO2H > CF3CO2H > C2H5OH > CH3CO2H 13. The rate of removal of the pain -killing drug paracetamol from the body is a first order reaction with a rate constant, k, of 0.26 h−1. How long will it take for 50% of the paracetamol ingested to remain in the body? A 0.26 h B 0.52 h C 2.7 h D 5.4 h

6 Jurong Junior College 8872/01/Prelim 2012 [Turn Over 14. The reaction of hydrogen peroxide with iodide ions in an acidic solution is first order with respect to hydrogen peroxide as well as iodide ions, and zero order with respect to hydrogen ions. H2O2(aq) + 2H+(aq) + 2I −(aq) → 2H2O(l) + I2(aq) Two experiments were carried out seperately. Which pair of diagram s represents the variation of [H2O2] and [H+] with time? Experiment 1: In the presence of excess I − Experiment 2: In the presence of excess I − and H2O2 A B C D 15. Some compounds of Period 3 elements dissolve in water to form aqueous solutions that are acidic, basic or neutral. Which one of the following sequences shows the order of decreasing pH of the resultant solutions formed when the following compounds are dissolved in water? A MgO, AlCl3, P4O10 B SiCl4, MgCl2, NaCl C PCl5, SiCl4, AlCl3 D Al2O3, MgO, SO2 [H+] time 0 [H+] time 0 [H2O2] time 0 [H+] time 0 [H2O2] time 0 [H+] time 0 [H2O2] time 0 [H2O2] time 0

7 Jurong Junior College 8872/01/Prelim 2012 [Turn Over 16. Methyl mercaptan, CH3SH, has a foul smell and is often used to impart a smell to natural gas. What will be formed when CH3SH is burned in an excess of air? A CO H2O SO2 B CO2 H2O H2S C CO2 H2O SO2 D CO2 H2O SO3 17. A Period 3 element H is a good conductor of electricity in the solid and liquid state s. It reacts violently with oxygen and water. Which of the following statements is correct about element H? A Element H has a giant metallic structure. B The mobile charged carriers of H in the solid state are ions and electrons. C When the oxide of H is added to water, the resulting solution turns Universal Indicator red. D The value of the first ionisation energy of element H is bigger than the value of first ionisation energy of argon. 18. How many of the isomeric alcohols with the formula C4H9OH will produce an alkene that has cis and trans isomers, on treatment with concentrated sulfuric acid? A 1 B 2 C 3 D 4 19. In which class of compound, in its general formula, is the ratio of hydrogen atoms to carbon atoms the highest? A alcohols B aldehydes C carboxylic acids D halogenoalkanes

8 Jurong Junior College 8872/01/Prelim 2012