EJC Prelim P1

© EJC [Turn Over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examination 2018 General Certificate of Education Advanced Level Higher 2 CHEMISTRY Paper 1 Multiple Choice 9729/01 24 September 2018 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, civics group and registration number on the Answer Sheet in the spaces provided unless this has been done for you. There are thirty 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 a wrong answer. Any rough working should be done in this question paper. The use of an approved scientific calculator is expected, where appropriate. This document consists of 12 printed pages.

2 © EJC 9729/01/J2PE/18 1 Following J. J. Thomson’s discovery of the electron in 1897, Ernest Rutherford devised the celebrated gold foil experiment, which led to a better understanding of the structure of the atom. In the experiment, a beam of heavy α particles, 42 2He + , was fired at a piece of thin gold foil as target. As expected, most of the α particles passed straight through the gold foil undeflected. However, some α particles are scattered, and a small number in fact deflected right back to the source. Which of the following conclusions cannot be drawn from the gold foil experiment? A Atom is mostly empty space. B Atom possesses a region of positive charge . C Electrons in atom orbit around a dense positively charged region. D The positive charge in an atom is concentrated within a very small volume. 2 The most common oxidation state of americium, Am, in aqueous solution is + n. Recently, Cu 3+ has been shown to quantitatively oxidise Am n+(aq) in dilute HNO 3 to the +2n oxidation state, while itself is reduced to Cu2+. In an experiment, 25.0 cm 3 of 0.0100 mol dm –3 Amn+(aq) was found to require 15.0 cm 3 of 0.0500 mol dm–3 Cu3+ for complete oxidation. What is the formula of the americium containing species formed? A Am 2+ B AmO 2 C 2AmO + D 2 2AmO + thin gold foil beam of α particles circular fluorescent screen source of α particles most α particles are undeflected some α particles are scattered

3 © EJC 9729/01/J2PE/18 [Turn Over 3 In which sequences are the molecules quoted in order of increasing bond angle around the central atom within the molecule? A OF 2 CH 4 SF 6 B H 2O O 3 N 2O C PF 3 BF 3 IF3 D NO 2 SO 2 CO 2 4 Unlike the reaction of ammonia with hydrogen chloride to give ammonium chloride, the reaction of ammonia with hydrogen fluoride produces colourless crystals of ammonium bifluoride, NH4HF2, which contains the bifluoride ion, HF2 –: NH3(g) + 2HF(g) → NH4HF2(s) Which of the following chemical bonds are present in the ammonium bifluoride crystals? 1 ionic bond 2 dative bond 3 hydrogen bond A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only 5 The value of pV is plotted against p for two gases, an ideal gas and a non-ideal gas, where p is the pressure and V is the volume of the gas. At which points on the graph, is the intermolecular forces of attraction within the non-ideal gas, the dominant factor accounting for deviation from ideal gas behavior? A W only B W and X only C W, X and Y only D W, X and Z only pV p ideal gas non-ideal gas W X Y Z

4 © EJC 9729/01/J2PE/18 6 There are conflicting interpretations for the origin of the acidity of aqueous boric acid, B(OH)3. Some believe that the acidity is exclusively from the following equilibria: B(OH)3(aq) + H2O(l) B(OH) 4 –(aq) + H+(aq) Which of the following statements pertaining to this interpretation of the acidity of boric acid is incorrect? A Boric acid is an Arrhenius acid. B Boric acid is a Brønsted-Lowry acid. C Boric acid is a Lewis acid. D Boric acid is a weak monobasic acid. 7 Chlorides of Period 3 elements dissolve in water to form aqueous solutions. Which of the following sequence shows the order of increasing pH of the resultant solutions formed when these compounds are dissolved in water? A Al2Cl6 < MgC l2 < NaC l B MgCl2 < A l2Cl6 < SiC l4 C PCl5 < MgC l2 < A l2Cl6 D SiC l4 < A l2Cl6 < PC l5 8 For the elements in Period 3 of the Periodic Table, which of the following sketches shows the correct trend in the stated property? A B C D 10 11 12 13 14 15 16 17 10 11 12 13 14 15 16 17 10 11 12 13 14 15 16 17 10 11 12 13 14 15 16 17 Na Mg A l Si P S C l atomic radius / nm melting point / ºC electronegativity Na Mg A l Si P S C l Na Mg A l Si P S C l electrical conductivity Na Mg A l Si P S C l

5 © EJC 9729/01/J2PE/18 [Turn Over 9 Sodium reacts with water to form sodium hydroxide and hydrogen. () ( ) ( ) () 222Na s 2H O 2NaOH aq H g+→ + l 1HΔ d What information is needed in order to calculate the standard enthalpy change of reaction, 1HΔ d ? 1 cHΔ d for H2(g) 2 cHΔ d for H2O(l) 3 fHΔ d for NaOH(aq) 4 cHΔ d for Na(s) A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 4 only 10 Which reaction represents a standard enthalpy change at 298 K? A () ()1 22 Og O g→ B () () () 22Cg O g C O g+→ C () () () 262C s 6H g C H g+→ D () () () ()42 2 2CH g 2O g CO g 2H O g+→ + 11 The reaction between ()Aa q and ()Ba q has a rate constant of 9×10−3 mol−2 dm6 s−1. Which one of the following is a possible rate equation for this reaction? A ()rate B aqk =  B () 2 rate A aqk =  C () () 2 rate A aq B aqk   =    D () () 22 rate A aq B aqk   =   

6 © EJC 9729/01/J2PE/18 12 The half-life of the first order gaseous reaction in which X 2 molecules become converted into X atoms is 20 minutes. 1 mol of X2 is put into a sealed vessel at pressure p. Which of the following will be correct when 87.5% of X2 has been converted into X atoms? 1 60 minutes have elapsed. 2 1.75 mol of X atoms have been formed. 3 The total pressure is 15 8 p (at constant temperature). A 1 only is correct B 1 and 2 only are correct C 2 and 3 only are correct D 1, 2 and 3 are correct 13 The graphs below show how the percentage of gaseous products present at equilibrium vary with temperature and pressure. Which one of the following reactions could the graph represent? A () ()24 2N O g 2NO gƒ ΔH = +57 kJ mol–1 B () () ()22Hg g 2 Hg+ II ƒ ΔH = +53 kJ mol–1 C () () () 22C s O g 2CO g+ ƒ ΔH = –221 kJ mol–1 D () () ()22 3N g 3H g 2NH g+ ƒ ΔH = –92 kJ mol–1 % products at equilibrium pressure T ºC (T + 10) ºC

7 © EJC 9729/01/J2PE/18 [Turn Over 14 L and M can react together to reach equilibrium in the reaction below. () () () ()g g g g++LM QR ˆˆˆ †‡ˆˆ ˆ In an experiment, 1.0 mole each of L and M were reacted at constant pressure P and temperature 350 ºC. The amount of R present in the mixture at intervals of time was recorded. The experiment was repeated at the same pressure P, but at a temperature of 700 ºC. The results for both experiments are shown below. Which one of the following information cannot be deduced from the graph? A The value of K p at 350 ºC. B The forward reaction is exothermic. C The activation energy of the forward reaction is high. D The equilibrium is achieved at a faster rate at higher temperatures. 15 The table gives the concentrations and pH values of the aqueous solutions of three compounds, X, Y and Z at 25 ºC. Each compound could be an acid or a base. X Y Z concentration 1.00×10−4 mo