CJC Prelim H2 Chem 2008 P1

CATHOLIC JUNIOR COLLEGE PRELIMINARY EXAM 2008 CHEMISTRY 9746/01 CHEMISTRY 9746/01 Higher 2 Higher 2 Paper 1 Multiple Choice 11 September 2008 Paper 1 Multiple Choice 11 September 2008 1 hour 1 hour Additional Materials: Mult iple Choice Answer Sheet Additional Materials: Mult iple Choice Answer Sheet Soft clean eraser Soft clean eraser Soft pencil Soft pencil Data Booklet Data Booklet READ THESE INSTRUCTIONS FIRST READ THESE INSTRUCTIONS FIRST Write in soft pencil. Write in soft pencil. Write your name, class and NRIC number on the Multiple Choice Answer Sheet in the spaces provided unless this has been done for you. Write your name, class and NRIC number on the Multiple Choice Answer Sheet in the spaces provided unless this has been done for you. There are forty questions in this paper. Answer all questions. For each question, there are four possible answers A, B, C and D. There are forty questions in 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. Choose the one you consider correct and record your choice in soft pencil on the separate Answer Sheet. Read the instructions on the Multiple Choice Answer Sheet very carefully. Read the instructions on the Multiple Choice Answer Sheet very carefully. Each correct answer will score one mark. A mark will not be deducted for a wrong answer. 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. Any rough working should be done in this booklet. This document consists of 11This document consists of 11 printed pages and 1 blank page.

2 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 expression correctly defines the term relative atomic mass of an element? A The mass of one atom of an element relative to the mass of one atom of 12C. B The mass of one mole of atoms of an el ement relative to the mass of one atom of 12C. C The mass of one mole of atoms of an el ement relative to the mass of one mole of 12C atoms. D The mass of one mole of atoms of an element divided by Avogadro’s constant. 2 How many atoms are there in 500 cm3 of carbon dioxide under room conditions? A 1.25 × 1022 B 1.34 × 1022 C 3.76 × 1022 D 9.0 × 1026 3 When 10 cm 3 of a gaseous hydrocarbon X were burned in 70 cm 3 of oxygen, the final gaseous mixture contained 30 cm 3 of carbon dioxide and 20 cm 3 of unreacted oxygen. [All gaseous volumes measured under identical conditions.] What is the formula of hydrocarbon X? A C 2H6 B C 3H6 C C 3H8 D C 4H10 4 20.0 cm 3 of 0.02 mol dm −3 bromate(V), BrO 3 −, was found to react completely with 80.0 cm 3 of 0.01 mol dm −3 hydroxylamine, NH 2OH. BrO 3 − ions are reduced as follows: B r O 3 – + 6e– + 6H+ → Br− + 3H2O Which of the following could be the half-equation for the oxidation of hydroxylamine? A NH 2OH → ½ N2O + 2H+ + ½ H2O + 2e− B NH 2OH + H2O → NO2 − + 5H+ + 4e− C NH 2OH → NO + 3H+ + 3e− D NH 2OH + 2H2O → NO3 − + 7H+ + 6e− CJC 2008 9746/01/prelim/08

3 5 The table below gives the successive ionisation energies, in kJ mol -1, of an unknown element X. First Second Third Fourth Fifth Sixth Ionisation energy 800 1550 7700 10500 13600 18000 Which of the following statements about X is correct? A The aqueous ion X+ is likely to be coloured. B X is a Group III element in the Periodic Table. C X is able to exhibit more than one oxidation state. D The oxide of X reacts readily with H+ to form a salt and water. 6 In an experiment, an ore sample cont aining phosphorus and an unknown element M is vapourised, ionised and passed through an electric field. _ P + M+ + Based on the diagram above, what is the likely identity of the unknown element M? A Sulphur B Silicon C Sodium D Nitrogen 7 Which of the following best describes the geometry of the following chlorides formed by the elements Al, Si and P? AlCl 3 SiCl 4 PCl 3 A Trigonal planar Square planar Trigonal planar B Trigonal planar Tetrahedral Trigonal pyramidal C Trigonal planar Tetrahedral T-shaped D Trigonal pyramidal Square planar Distorted tetrahedral 8 The values of the ionic radii, in nm, of several ions are given below: Li+ 0.060 F − 0.136 Na+ 0.095 Cl − 0.181 Mg2+ 0.065 O 2− 0.140 Ca2+ 0.099 Which of the following compounds, all of which have the same crystal structure, has the greatest lattice energy? A LiF B NaCl C MgO D CaO CJC 2008 9746/01/prelim/08

4 9 When 0.2 mol of zinc dust was added to 250 cm 3 of 1.0 mol dm -3 aqueous copper(II) sulphate (an excess), the temperature of the solution rose by 15 °C. The specific heat capacity of the final solution is 4.20 J g-1 K-1. What is the enthalpy change for the reaction Cu2+ + Zn → Zn2+ + Cu ? A -78.8 kJ mol -1 C -15.8 kJ mol -1 B -39.4 kJ mol -1 D -3.15 kJ mol -1 10 Given the following enthalpy changes: C 6H4(OH)2 (aq) → C6H4O2 (aq) + H2 (g) ΔHθ = +177 kJ mol-1 H 2O2 (aq) → H2O (l) + ½ O2 (g) ΔHθ = -95 kJ mol-1 H 2 (g) + ½ O2 (g) → H2O (l) ΔHθ = -286 kJ mol-1 What is the enthalpy change for the following reaction? C 6H4(OH)2 (aq) + H2O2 (aq) → C6H4O2 (aq) + 2H2O (l) A -490 kJ mol -1 C -204 kJ mol -1 B -368 kJ mol -1 D -82 kJ mol -1 11 Which of the following reactions will have a negative ∆S value? A CO 2 (g) + C (s) → 2 CO (g) B NH 4NO3 (s) → N2O (g) + 2 H2O (g) C 2 H 2O2 (aq) → 2 H2O (l) + O2 (g) D PH 3 (g) + HI (g) → PH4I (s) 12 Two cells are connected in series as shown in the diagram where M, N, O and P are electrodes. 1 mol dm-3 dil HNO3 1 mol dm-3 FeCl3 (aq) platinum O P M N lead Which of the following correctly shows the products formed at each electrode? M N O P A O2 H 2 O 2 Fe 2+ B O2 Pb Cl2 H 2 C Pb2+ H 2 Cl 2 H 2 D Pb2+ H 2 O 2 Fe 2+ CJC 2008 9746/01/prelim/08

5 13 Consider the reversible reaction: A (g) + 3B (g) AB 3 (g) Equilibrium was esta blished in a 0.2 dm 3 vessel at a temperat ure of 900 K. The diagram below shows the change in number of moles of AB 3 and B with time. The initial number of moles of A was 0.2. no. of moles AB3 0.5 0.3 0.4 0.2 0 0.1 What is the equilibrium constant Kc for the reaction in mol-3 dm9? A B C D B 0.5 time 0.5 0.5 0.5 0.2x (0.1)3 0.1x (0.2)3 (0.2)4 0.1 14 Silver chromate(VI), Ag 2CrO4, is sparingly soluble in water. In its saturated solution, the concentration of Ag2CrO4 is 6.5 x 10 -5 mol dm-3. What is the numerical value of the Ksp of Ag2CrO4? A 2.75 x 10 -13 B 1.10 x 10-12 C 4.23 x 10-9 D 8.45 x 10-9 15 In which of the following sequences is the value of pKa decreasing? A C 6H5OH > CH3CH2CH2CHClOH > CH3CH2CH2CH2OH > (CH3)3COH B (CH 3)3COH > CH3CH2CH2CH2OH > CH3CH2CH2CHClOH > C6H5OH C CH 3CH2CH2CH2OH > (CH3)3COH > CH3CH2CH2CHClOH > C6H5OH D CH 3CH2CH2CHClOH > (CH3)3COH > CH3CH2CH2CH2OH > C6H5OH 16 A piece of zinc foil dissolved completely in 20 cm 3 of a dilute sulphuric acid solution and the volume of hydrogen evolved was not ed at equal, short time intervals. Another piece of zinc fo il of the same surface area and mass was added to 40 cm 3 of the same solution of sulphuric acid. How will the initial rate of reaction and the total volume of hydrogen evolved in this second experiment compare to the first experiment? initial rate of reaction tota l volume of hydrogen evolved A no change decrease B no change no chan