AJC H2 Chem 2012 Prelim P1 QP

ANDERSON JUNIOR COLLEGE Preliminary Examinations 2012 CHEMISTRY 9647/01 Higher 2 19 September 2012 Paper 1 Multiple Choice 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. 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 Multiple Choice Answer Sheet. 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. Multiple Choice Answer Sheet Write your name, PDG and NRIC/FIN number, including the reference letter. Shade the NRIC / FIN number. Exam Title: JC 2 Prelim Exam Details: H2 Chem / Paper 1 Date: 19/09/2012 This document consists of 17 printed pages. AJC Prelim 2012 9647/01/H2 [Turn over

2 AJC Prelim 2012 9647/01/H2 Section A For each question there are four possible answers, A , B, C and D. Choose the one you consider to be correct. 1 The first stage in the manufacture of nitric acid is the oxidation of ammonia by oxygen. aNH3(g) + bO2(g) cNO(g) + dH2O(g) What are the values for a, b, c and d? a b c d A 4 5 4 6 B 4 6 4 5 C 5 6 5 4 D 6 5 6 4 2 The nickel–cadmium rechargeable battery is based on the following overall reaction. Cd + 2NiOOH + 4H2O Cd(OH)2 + 2Ni(OH)2.H2O What is the oxidation number of nickel at the beginning and at the end of the reaction? Beginning End A +1.5 +2 B +2 +3 C +3 +2 D +3 +4 3 Which element has an equal numbe r of paired and unpaired electrons in its orbitals with principal quantum number 2? A Beryllium B Carbon C Nitrogen D Oxygen

3 AJC Prelim 2012 9647/01/H2 [Turn over 4 Americium–241 is commonly used in smoke detectors. It works by emitting a constant stream of alpha particles which are similar to the nucleus of 4He. Strontium–90 is another radioactive substance which can be used as a tracer for medicinal or agriculture uses. On decaying, it emits beta particles which can be considered as electrons. A small a mount of Americium –241 and Strontium –90 are separately placed in an ionisation chamber to emit a constant stream of radiation and the emitted particles are passed through an electric field. What would be the path of the emitted particles in an electric field? Americium–241 (a–particles) Strontium–90 (b–particles) A 1 2 B 1 3 C 4 1 D 3 1 5 Which of the following is not a feature in the corresponding ion? Ion Feature A HF2– Hydrogen bond B NO2– Unpaired electron C CO32– Delocalised electrons D C6H5O– All bond angles are 120° 1 2 3 4 + –

4 AJC Prelim 2012 9647/01/H2 6 Two gas bulbs, E and F, are connected by a stopcock. Bulb E contains argon and bulb F contains oxygen gas. The pressure and volume of gas in each bulb at 25 °C is shown below. Bulb E Bulb F Volume / dm3 v 7v Pressure / kPa p 5p The stopcock is then opened and the gases were allowed to mix at 25 °C. Subsequently, the temperature of the mixture is raised and the final pressure is found to be 9p. What is the temperature of the gases in the mixture that gives a pressure of 9p? A 50 °C B 596 °C C 50 K D 596 K 7 Solutions of hydrogencarbonates can react with acids as follows. HCO3–(aq) + H+(aq) H2O(l) + CO2(g) DHo = +12.7 kJ mol–1 Given the following enthalpy changes: species DH q f / kJ mol–1 H2O(l) –285.8 CO2(g) –393.5 HCO3–(aq) –692.0 What is the standard enthalpy change of formation of H+(aq)? A –25.4 kJ mol–1 B 0.0 kJ mol–1 C +25.4 kJ mol–1 D +1384 kJ mol–1 8 The Gibbs free energy change of a system determines whether a reaction is spontaneous, while the equilibrium constant indicates the extent of reaction. What does the following pair of values for a reaction system indicate? values DGq f –50.8 Kc 5.80 x 108 A No reaction B Position of equilibrium lies to the left C Some extent of reaction D Reaction goes to completion

5 AJC Prelim 2012 9647/01/H2 [Turn over 9 The electrolysi s of a highly concentrated aqueous solution of potassium h ydroxide was carried out using an iron anode and a platinum cathode. After a current was passed through the cell for some time, 360 cm3 of gas was collected at the cathode (measured at r.t.p.) while there was a loss of mass of 0.279 g at the anode. Which of the following ions is a likely product at the anode? A Fe2+ B Fe3+ C FeO44– D FeO42– 10 The percentage of ammonia obtainable, if equilibrium w as established during the Haber process, is plotted against the operating pressure for two temperatures, 400 °C and 500 °C. Which diagram correctly represents the two graphs? A B pressure/ 103 kPa % NH3 at equilibrium pressure/ 103 kPa % NH3 at equilibrium C D pressure/ 103 kPa % NH3 at equilibrium pressure/ 103 kPa % NH3 at equilibrium

6 AJC Prelim 2012 9647/01/H2 11 Water dissociates into H+ and OH– as shown. H2O H+ + OH– At 25 °C, the equilibrium [H +] is 10–7 mol dm–3; [H2O] = 55.6 mol dm–3. What is the order of increasing numerical value of pH, pK a and pKw for this equilibrium at this temperature? smallest largest A pH pKw pKa B pH pKa pKw C pKw pKa pH D pKa pKw pH 12 Bromocresol green is an acid –base indicator with a pH range of 3.8 to 5.4. The acidic colour of the indicator is yellow and the alkaline colour is blue. Two drops of the indicator are added to each of the four aqueous solutions listed below. Which solution has its colour not correctly stated? A Aqueous solution of MgCl2 blue B Equal p roportions of sodium e thanoate a nd ethanoic acid [pKa of ethanoic acid = 4.7] green C Dilute HCl of concentration 3.0 x 10–5 mol dm–3 yellow D Aluminium oxide in aqueous solution blue 13 Lead is the final product formed by a series of changes in which the rate –determining step is the radioactive decay of uranium –238. The radioactive decay is a first order reaction with a half–life of 4.5 x 109 years. What would be the age of a rock sample, originally lead– free, in which the molar proportion of uranium to lead is now 1:3? A 2.25 x 109 years B 4.5 x 109 years C 9.0 x 109 years D 13.5 x 109 years

7 AJC Prelim 2012 9647/01/H2 [Turn over 14 Na2S2O3 reacts with dilute HC l to give a pale yellow precipitate. If 1 cm 3 of 0.1 mol dm –3 HCl is added to 10 cm 3 of 0.02 mol dm –3 Na2S2O3 the precipitate forms slowly. If the experiment is repeated with 1 cm 3 of 0.1 mol dm –3 HCl and 10 cm 3 of 0.05 mol dm –3 Na2S2O3 the precipitate forms more quickly. Which of the following helps to explain this observation? A The activation energy of the reaction is lower when 0.05 mol dm–3 Na2S2O3 is used. B The reaction proceeds by a different pathway when 0.05 mol dm–3 Na2S2O3 is used. C The collisions between reactant particles are more violent when 0.05 mol dm –3 Na2S2O3 is used. D The reactant particles collide more frequently when 0.05 mol dm–3 Na2S2O3 is used. 15 Consecutive elements G, H and I are in the third period of the Periodic Table. Element H has the highest first ionisation energy and the lowest melting point. What could be the identities of G, H and I? A Aluminium, silicon, phosphorus B Magnesium, aluminium, silicon C Silicon, phosphorus, sulfur D Sodium, magnesium, aluminium 16 Use of the Data Booklet is relevant to this question. A 5.00 g sample of an anhydrous Group II metal nitrate loses 3.29 g in mass when heated strongly. Which metal is present? A Magnesium B Calcium C Strontium D Barium 17 Which suggestion concerning the element as