2021 MI Prelim P1 Ans

Class Adm No Candidate Name: This question paper consists of 14 printed pages and 2 blank pages. 2021 End-of-Year Examinations Pre-University 2 H1 CHEMISTRY 8873/01 Paper 1 Multiple Choice 22nd Sep 2021 1 hour Additional materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Do not turn over this question paper until you are told to do so. Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and admission number in the spaces provided at the top of this page and on the Multiple Choice Answer Sheet provided. 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 Multiple Choice Answer Sheet provided. 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 question paper. The use of an approved scientific calculator is expected, where appropriate. FOR EXAMINER’S USE TOTAL (30 marks)

2 1 Magnetite, Fe3O4, is an equimolar mixture of iron(II) oxide, FeO, and iron(III) oxide, Fe2O3. 3.48 g of magnetite is dissolved in excess dilute sulfuric acid. 25.0 cm3 of K2Cr2O7(aq) exactly oxidises the dissolved Fe2+ present according to the equation. Cr2O72- (aq) + 14H+ (aq) + 6Fe2+ (aq) → 2Cr3+ (aq) + 7H2O (l) + 6Fe3+ (aq) What is the concentration, in mol dm–3, of the K2Cr2O7(aq) used? A 0.01 B 0.05 C 0.10 D 0.20 2 What are the oxidation states of oxygen in the following compounds? O2 OF2 H2O2 A 0 -2 -1 B 0 +2 -1 C -2 -2 -2 D -2 +2 -2 3 An acidified solution of the salt KClO2 oxidises Ti3+(aq) to Tin+(aq) while the chlorine is reduced to C l(aq). When 0.00245 mol of KC lO2 reacted with 0.400 mol dm 3 Ti3+(aq), 24.50 cm 3 of Ti3+(aq) was needed for complete reaction. What is the value of n? A 1 B 2 C 3 D 4 4 An ion X2+ contains 24 protons. What is the electronic configuration of X2+? A 1s2 2s2 2p6 3s2 3p6 3d4 B 1s2 2s2 2p6 3s2 3p6 3d2 4s2 C 1s2 2s2 2p6 3s2 3p6 3d5 4s1 D 1s2 2s2 2p6 3s2 3p6 3d6 4s2

3 [Turn over 5 The table gives the successive ionisation energies for an element G. 1st 2nd 3rd 4th 5th 6th Ionisation energy / kJ mol1 750 1800 3700 5600 16000 20300 What is the formula of the chloride of G? A GCl B GCl2 C GCl3 D GCl4 6 Which of the following pairs of molecules have the same shape? A AlCl3 and PCl3 B SO3 and BF3 C NH3 and BCl3 D SO2 and CO2 7 Which of the following statements about graphite is incorrect? A All the bond angles in it are 120o. B Each carbon atom is bonded to three other carbon atoms. C It is able to conduct electricity due to the presence of delocalised electrons that are free to move within each layer. D It has low melting point due to the weak instantaneous dipole-induced dipole interactions between the layers.

4 8 The diagram shows the structure of part of a crystal of ice. Which statements about this structure are correct? 1 The open structure of ice causes ice to be less dense than water. 2 The hydrogen bonds, shown by the dotted lines, are stronger than the O -H covalent bonds. 3 All the bond angles surrounding each oxygen atom is 105⁰. 4 Four electrons from each oxygen are involved in forming hydrogen bonds. A 1 and 4 only B 2 and 3 only C 2 and 4 only D 1, 3 and 4 only 9 The lattice energies of rubidium fluoride, RbF, and caesium chloride, CsC l, are 760 kJ mol 1 and 650 kJ mol1, respectively. Which value is likely to be the lattice energy of caesium fluoride, CsF, in kJ mol−1? A 460 kJ mol1 B 550 kJ mol1 C 680 kJ mol1 D 800 kJ mol1

5 [Turn over 10 When equal masses of X and Y absorb the same amount of energy, their temperatures rise by 5 °C and 10 °C respectively. Which of the following statements is correct? A The specific heat capacity of X is twice that of Y. B The specific heat capacity of X is half that of Y. C The specific heat capacity of X is one fifth that of Y. D The specific heat capacity of X is the same as Y. 11 I2(g) + 3Cl2(g)  2 ICl3(s) H o— = –214 kJ mol–1 I2(s)  I2(g) H o— = +38 kJ mol–1 What is the standard enthalpy change of formation of iodine trichloride, ICl3(s)? A +176 kJ mol–1 B –88 kJ mol–1 C –176 kJ mol–1 D –214 kJ mol–1

6 12 The graph shows the Maxwell–Boltzmann energy distribution curve for a given gas at a certain temperature. How will the curve change if the temperature of the gas is increased, while other conditions remain constant? 1 Maximum becomes higher 2 Graph shifted right 3 Area under the graph becomes larger A 1 only B 2 only C 1 and 2 only D 2 and 3 only

7 [Turn over 13 The dotted line represents the formation of oxygen, O 2 (g), from the uncatalysed complete decomposition of hydrogen peroxide, H2O2 (aq). Which curve represents a catalysed reaction under the same conditions? Ans: B 14 The equilibrium constant Kc for the following reaction increases with temperature. X (s) ⇌ Y (s) + Z (g) What deduction can be made from this information? A The yield will increase at higher pressure. B The forward reaction is endothermic. C The value of Kc depends on the amount of X used. D The yield is independent of temperature. Volume of oxygen / dm3

8 15 Ammonia is manufactured industrially by the Haber Process as shown. N2(g) + 3H2(g) 2NH3(g) H < 0 The operating conditions are: 400 to 450 °C; a pressure of 200 atm; an iron catalyst Which of the following statements are true about the Haber process for the manufacture of ammonia? 1 At higher temperatures, the yield goes down but the rate of production of ammonia is faster. 2 At higher pressures, the yield goes down but the rate of production of ammonia is faster. 3 The presence of a catalyst shifts the equilibrium position to the right and increases the yield. A 1 only B 2 only C 1 and 2 only D 1, 2 and 3 16 Which of the following is a Lewis acid but not a Brønsted−Lowry acid? 1 CH3COOH 2 AlCl3 3 HF A 1 only B 2 only C 1 and 2 only D 2 and 3 only

9 [Turn over 17 Stomach juice has a pH of 1.0. Aspirin is a monobasic acid represented by HX (Ka = 10-14 mol dm-3) which dissociates into ions of H+ and X–. What are the relative concentrations of H +, X– and HX when an aspirin tablet is ingested and enters into the stomach? A [HX]  [H+] = [X–] B [H+]  [X–]  [HX] C [H+] = [X–]  [HX] D [H+]  [HX]  [X–] 18 Which of the following could act as buffers? 1 A 1:2 mixture of HCl and NH3 2 A 2:1 mixture of NaOH and H2CO3 3 A 1:1 mixture of NaH2PO4 and Na2HPO4 A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 3 only 19 Which of the following oxides will dissolve in water to give the solution with the lowest pH? A Al2O3 B MgO C P4O10 D SiO2

10 20 Which of the following statements concerning the third period elements (sodium to sulfur) and their compounds is correct? 1 The elements become more electronegative from sodium to chlorine. 2 Aluminium oxide is the only oxide in Period 3 which is amphoteric. 3 pH of the chlorides increases across the Period 3 elements. A 2 only B 1 and 2 only C 1 and 3 only D 2 and 3 only 21 The graphs below show the variation in two properties of the elements Na to S. Graph 1 Graph 2 Which properties are illustrated in Graphs 1 and 2?