CJC H2 CHEM P1 Prelim

CATHOLIC JUNIOR COLLEGE JC2 PRELIMINARY EXAMINATIONS Higher 2 CHEMISTRY 9647/01 Paper 1 Multiple Choice FRIDAY 16 SEPTEMBER 2011 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 and/or shade your name, NRIC / FIN number and HT group on the Multiple Choice Answer Sheet in the spaces provided. There are 40 MCQ 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. 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. Any rough working should be done in this booklet. Calculators may be used. This document consists of 18 printed pages. [Turn over]

2 9647/01/CJC JC2 Prelim Exam 2011 Section A 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 in soft pencil on the separate Answer Sheet provided. 1 Use of the Data Booklet is relevant to this question. How many atoms of oxygen are present in 24 cm3 of oxygen gas under room conditions? A 24  6.02  1023 32 B 23106.02 24000242   C 24000 106.022 23 D 1000 106.022 23 2 5.00 g of a fertilizer containing ammonium sulfate was dissolved in water and diluted to 250 cm 3. 25.0 cm3 of this solution was added to an excess of sodium hydroxide solution. The reaction between ammonium sulfate and s odium hydroxide is given by the following equation: (NH4)2SO4 + 2 NaOH → Na2SO4 + 2 H2O + 2 NH3 The ammonia produced was passed into 50.0 cm3 of 0.050 mol dm-3 sulfuric acid solution. The residual acid then required 25.80 cm3 of 0.100 mol dm-3 sodium hydroxide solution for complete neutralisation. What is the percentage by mass of ammonium sulfate (Mr = 132.1) in the fertiliser? A 10.6% B 16.0% C 32.0% D 40.0% 3 A student made up a 0.100 mol dm -3 solution of Ba(OH) 2.8H2O which he found in the laboratory cupboard and left the solution in an open beaker. A week later, he returned to the laboratory, used the solution for titration with 0.100 mol dm -3 HCl and was surprised to discover his titres were lower than expected. Which one of the following reasons explains why the volumes of HC l used were lower than expected? A Some water had evaporated from the barium hydroxide solution. B The concentration of HCl was less than the stated 0.100 mol dm-3. C The barium hydroxide crystals had less water of crystallization than stated. D Some of the barium hydroxide had reacted with carbon dioxide in the air to form solid barium carbonate.

3 9647/01/CJC JC2 Prelim Exam 2011 4 Which of the following electronic configurations represents an element that most likely forms a simple ion with a charge of -3? A 1s 2 2s22p6 3s23p1 B 1s 2 2s22p6 3s23p3 C 1s 2 2s22p6 3s23p63d3 4s2 D 1s 2 2s22p6 3s23p63d7 4s2 5 Which graph best represents the behaviour of a fixed mass of ideal gas under the given conditions? (where ρ is the density of the gas) A B C D 6 In which one of the following pairs of species is the melting point of the first member lower than that of the second member? A diamond, graphite B H 2O, NH3 C Br 2, ICl D pentane, 2,2-dimethylpropane V P 1 Constant P Constant T T V P T P ρ Constant T Constant V

4 9647/01/CJC JC2 Prelim Exam 2011 7 Adrenaline is a hormone which, when secreted directly into the blood stream, acts as a stimulant. It has the following structure: What are the values of angle E and angle F in a molecule of adrenaline? angle E angle F A 120o 107 o B 120o 90 o C 109o 107 o D 109o 90 o 8 Ammonia is manufactured industrially via the Haber process where nitrogen and hydrogen is passed through an iron catalyst at high temperature and pressures. Which of the following statements is true for the above reaction? A The activation energy of the forward and backward reaction is the same. B An increase in temperature increases the rate constant but decreases the equilibrium constant. C The reaction is carried out at high temperatures because it will favour the formation of ammonia. D Increasing the concentration of H 2 and N 2 causes the equilibrium constant of the reaction to increase as more ammonia is formed. 9 Which of the following processes is spontaneous only at high temperatures? A 2 CO(g) + 2 NH3(g)  C2H6(g) + 2 NO(g) H = +409 kJ mol-1 B 2 NO(g) + O2(g)  2 NO2(g) H = 114 kJ mol-1 C N 2O(g)  N2(g) + ½ O2(g) H =  82 kJ mol-1 D CO 2(g) + 2 H2O(l) → CH4(g) + 2 O2(g) H = +890 kJ mol-1

5 9647/01/CJC JC2 Prelim Exam 2011 10 Gallstones can form in the gall bladder. Patients who have gallstones may experience great pain. The component of gallstones is calcium ethanedioate which is insoluble in water. The corresponding magnesium ethanedioate is however, soluble in water. Which factor accounts for the difference in the solubility between magnesium ethanedioate and calcium ethanedioate? A Magnesium ethanedioate has a lower solubility product than calcium ethanedioate. B Magnesium ethanedioate has a lower lattice energy than calcium ethanedioate. C Magnesium ions have a higher hydration energy than calcium ions. D Magnesium is less electropositive than calcium. 11 Two substances A and B react according to the following equation: A + 2 B  C To determine the order of reaction with respect to each substance, four experiments were performed and the results are shown below: Experiment [A] / mol dm -3 [B] / mol dm-3 Initial rate of formation of C / mol dm-3 min-1 1 0.10 0.10 0.0010 2 0.40 0.10 0.0160 3 0.10 0.20 0.0020 4 0.20 0.20 ? Which is the correct value for the initial rate of formation of C for experiment 4? A 0.0040 B 0.0080 C 0.0160 D 0.0320 12 The pH of normal human blood is 7.4. Strenuous exercise can cause the condition called acidosis in which the pH falls. If the pH drops to 6.8, death may occur. How many times greater is the hydrogen ion concentration in blood at pH 6.8 compared to that at pH 7.4? A 0.3 B 0.6 C 1.1 D 4.0

6 9647/01/CJC JC2 Prelim Exam 2011 13 Which of the following statements explain why silver chloride is soluble in aqueous ammonia, but silver iodide is not? A The solubility product of silver iodide is numerically larger than that of silver chloride. B The equilibrium constant for AgX(s) + 2 NH 3(aq) ⇌ Ag(NH 3)2X(aq) is numerically larger for X = Cl than that for X = I. C The lattice energy of silver chloride is num erically larger than that of silver iodide. D Ammonia is a more powerful ligand that can displace chloride but not iodide ions. 14 During electroplating, a current is passed through a cell containing aqueous silver nitrate using inert electrodes. After a certain time, 2.70 g of silver was deposited at one electrode. What volume of gas would be produced at the other electrode at r.t.p.? A 70 cm 3 B 75 cm 3 C 140 cm 3 D 150 cm 3 15 Two separate students accidentally spilled chemicals on their clothes in the laboratory which resulted in brown MnO 2 stains and I2 stains. Their teacher suggested the use of bleaching agent (H2O2) for removal of these stains. The relevant standard redox potentials are listed below: I2 + 2 e- ⇌ 2 I- E o= +0.54 V MnO2(s) + 4 H+(aq) + 2 e- ⇌ Mn2+(aq) + 2 H2O(l) E o= +1.23 V H2O2 + 2 H+ + 2 e- ⇌ 2 H2O