MI H1 CHEM 8873 01 Answers

Class Adm No Candidate Name: This question paper consists of 13 printed pages and 1 blank page. 2018 End-of-Year Exams Pre-University 2 H1 CHEMISTRY 8873/01 Paper 1 Multiple Choice 13 Sept 2018 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 Section A For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 According to the equation below, how many moles of potassium chlorate, KC lO3, must be decomposed to generate 1000 cm3 of O2 gas at standard temperature and pressure? 2KClO3(s)  2KCl(s) + 3O2(g) A 2 3 ൬ 1 24൰ mol B 3 2 ൬ 1 24൰ mol C 2 3 ൬ 1 22.7൰ mol D 3 2 ൬ 1 22.7൰ mol 2 Use of the Data Booklet is relevant to this question. It is suggested that SO2 which contributes to acid rain, could be removed from a stream of waste gases by bubbling the gases through 0.25 mol dm -3 KOH, thereby producing K 2SO3. What is the maximum mass of SO2 that could be removed by 1000 dm3 of the KOH solution? A 4.0 kg B 8.0 kg C 16.0 kg D 20.0 kg

3 [Turn over 3 To determine the molar mass of a weak monoprotic acid, a student titrated 25.0 cm3 of the acid with aqueous NaOH. Which of the following are appropriate indicators that could be used for the titration? 1 Phenolphthalein 2 Methyl Orange 3 Bromothymol blue A 1 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 4 A sample of 30.0 cm 3 of 0.050 mol dm -3 iron( II) sulfate is titrated against 0.025 mol dm -3 potassium manganate(VII) solution. It is found that 20.0 cm 3 of the manganate(VII) solution is required to reach end point. What is the oxidation number of manganese at the end point? A +2 B +3 C +4 D +5

4 5 The number of orbitals of a principal quantum number is dependent on the type of subshell. Which of the following statements about the s, p and d orbitals of principal quantum numbers 1, 2 and 3 are true? 1 Each s orbital can hold a minimum of two electrons. 2 There are 3 orbitals in a 2p subshell. 3 The s orbital has a lower energy than the p orbital with the same principal quantum number. A 3 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 6 In the equilibrium represented below, which of the following species act as bases? HSO 4- + H2O ⇌ H3O+ + SO42- 1 HSO4- 2 H2O 3 SO42- A 3 only B 1 and 2 only C 2 and 3 only D 1,2 and 3 7 Which of the following can be classified as a Lewis acid? A An ion which accepts a pair of electrons to form a bond. B A molecule which donates a pair of electrons to form a bond. C A ion which accepts a proton from water. D A molecule which donates a proton to water.

5 [Turn over 8 Which of the following is a non-polar molecule that contains polar bonds? A F2 B CHF3 C CO2 D NH3 9 Which of the following species has a see-saw structure? A BrF4+ B BrF4- C IF5 D SO42- 10 The energy profile diagram for the reaction X + Y  Z is shown below. Which of the indicated energy differences is affected by the addition of a catalyst? A I only B II only C III only D I and II only

6 11 Calcination is a process which converts sodium hydrogen carbonate, NaHCO 3, to sodium carbonate, water and carbon dioxide. The balanced equation for the reaction is given below. 2NaHCO3(s) → Na2CO3(s) + H2O(l) + CO2(g) Standard enthalpy change of formation of NaHCO3(s) / kJ mol-1 -951 Standard enthalpy change of formation of Na2CO3(s) / kJ mol-1 -1131 Standard enthalpy change of formation of H2O(l) / kJ mol-1 -286 Standard enthalpy change of formation of CO2(g) / kJ mol-1 -394 What is the standard enthalpy change for the calcination reaction? A +860 kJ mol-1 B +91 kJ mol-1 C -91 kJ mol-1 D -860 kJ mol-1 12 Which of the following is associated with a relatively slow rate of a chemical reaction? A high temperature B low activation energy C strong bonds in reactant molecules D high concentration of reactants 13 The radioactive decay of a sample of 131I follows a first order kinetics. If a pure sample of 131I undergoes radioactive decay and the half-life of the decay was found to be 10 days, what would be the half-life of the decay in a separate experiment where the initial concentration of the pure sample of 131I was doubled? A 2.5 days B 5 days C 10 days D 20 days

7 [Turn over 14 The following table shows the results from a rate study of the reaction X + Y  Z. Experiment [X] / mol dm-3 [Y] / mol dm-3 Initial rate of formation of Z / mol dm-3 s-1 1 0.40 0.10 R 2 0.20 0.20 ? Starting with known concentrations of X and Y in experiment 1, the rate of formation of Z was measured. If the reaction was first order with respect to X and second order with respect to Y, what is the initial rate of formation of Z in experiment 2? A R 4 B R 2 C R D 2R 15 Equal amounts of HC l and O 2 in a closed system are allo wed to reach equilibrium as represented by the equation below. Which of the following must be true at equilibrium? 4HCl(g) + O 2(g) ⇌ 2Cl2(g) + 2H2O(g) 1 [HCl] must be less than [Cl2] 2 [O2] must be greater than [HCl] 3 [Cl2] must equal [H2O] A 3 only B 1 and 2 only C 2 and 3 only D 1,2 and 3

8 16 Carbon dioxide dissolves in water sparingly to produce carbonic acid, H2CO3. CO2(g) + H2O(l) ⇌ H2CO3(aq) Carbonic acid further dissociates in water according to the two equations below. H2CO3(aq) + H2O(l) ⇌ H3O+(aq) + HCO3–(aq) HCO3–(aq) + H2O(l) ⇌ H3O+(aq) + CO32–(aq) How would the addition of a small amount of NaOH(aq) affect [CO2], [HCO3–] and [CO32–] when carbon dioxide dissolves in water? [CO 2] [HCO3–] [CO 32–] A decrease decrease increase B decrease negligible change increase C decrease Increase increase D increase negligible change decrease 17 Which of the following statements concerning the characteristics of halogens is incorrect? A The fourth ionisation energies decrease as the atomic numbers of the halogens increase. B Fluorine is the strongest oxidising agent. C The ease of decomposition of hydrogen halides decreases down Group 17. D The acid strength of an aqueous solution of the hydrogen halides increases from HC l to HI. 18 Which of the following elements from Period 3 (sodium to chlorine) in the Periodic Table forms an oxide which dissolves in water to form a solution of pH 13? A Sodium B Silicon C Sulfur D Chlorine

9 [Turn over 19 [Al(H2O)6]3+ ion is hydrolysed in aqueous solution according to the equation below. [Al(H2O)6]3+(aq) +