ACSI 2018 Prelim Paper 1

Anglo-Chinese School (Independent) Year 6 Preliminary Examination 2018 INTERNATIONAL BACCALAUREATE DIPLOMA PROGRAMME CHEMISTRY HIGHER LEVEL PAPER 1 Tuesday 11th September 2018 1 hour Additional materials: Multiple choice answer sheet Soft clean eraser Soft pencil (type 2B recommended) INSTRUCTIONS TO CANDIDATES Do not open this booklet until you are told to do so. Write your Candidate number and the subject on the separate answer sheet provided. There are forty questions in this paper. Answer all the 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. INFORMATION FOR CANDIDATES 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. A copy of the periodic table is provided for reference on Page 2 of the examination paper. Calculators are not allowed to be used in this paper. This question paper consists of 16 printed pages, including the cover page.

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3 1. Group 2 ionic hydrides react with water as follows: CaH2 + 2H2O → Ca(OH) 2 + 2H2 In an experiment, a certain mass of calcium hydride was dissolved in excess water. The resulting solution required 20.0 cm 3 of a 2.00 mol dm −3 HCl solution for complete neutralization. What was the mass of calcium hydride? A. 0.421 g B. 0.571 g C. 0.741 g D. 0.842 g 2 How many molecules are present in 1 cm 3 of oxygen gas under room conditions? (1 mol of gas occupies 24000 cm3) A. 1 × 24000 6.02 × 1023 B. 1 × 6.02 × 1023 24000 C. 6.02 × 1023 × 24000 1 × 1000 D. 1 × 6.02 × 1023 ×16 3. What do the ions 34P3− and 34S2− have in common? A. Both ions contain the same number of neutrons in their nuclei. B. Both ions have more neutrons than electrons. C. Both ions have an electronic configuration of [Ne] 3s2 3p6. D. Both ions have 16 protons in their nuclei. 4. Which electron transition in the hydrogen atom emission spectrum emits radiation with the shortest wavelength? A. n = 2 → n = 1 B. n = 3 → n = 2 C. n = 3 → n = 1 D. n = 4 → n = 3

4 5. The successive ionization energies of two elements, Q and R, are given. Ionization energies / kJ mol−1 1st 2nd 3rd 4th 5th 6th 7th 8th Q 740 1450 7720 10540 13630 18020 21700 25660 R 1011 1907 2910 4960 6270 21270 25431 29872 What is the formula of the compound formed when Q reacts with R? A. Q3R2 B. Q2R3 C. Q3R4 D. Q2R5 6. Which compound will be diamagnetic? A. [Cr(H2O)6)]Cl3 B. [Fe(H2O)6)]Cl2 C. [Zn(H2O)6)]Cl2 D. [MnCl4]2− 7. Which compound is not a product of the reaction between an oxide of a period 3 element and water? A. NaOH B. Al(OH)3 C. H3PO4 D. H2SO3 8. Which element in period 3 is not correctly described? element bonding structure A. sodium metallic giant metallic B. silicon covalent simple molecular C. sulfur covalent simple molecular D. chlorine covalent simple molecular

5 9. Which statements are correct about the carbon to oxygen bond length in the following substances? I. The carbon to oxygen bond lengths are equal in ethanedioic acid, (COOH)2. II. The carbon to oxygen bond length in carbon monoxide is shorter than the carbon to oxygen bond length in carbon dioxide. III. The carbon to oxygen bond lengths in the methanoate ion, HCOO−, are equal. A. I and II only B. I and III only C. II and III only D. I, II and III 10. Which of the following molecules is non-polar? A. PCl3 B. XeF4 C. SO2 D. HCHO 11. Which of the following statements best describes silicon dioxide, SiO2? A. Each silicon atom is covalently bonded to four oxygen atoms. B. Each oxygen atom forms double covalent bond with silicon atom. C. The angle formed between the atoms is 120o. D. The silicon and oxygen atoms are arranged in layers which slide easily over one another.

6 12. What is the hybridization of the N atom in NO3− and NO2− respectively? NO3− NO2− A. sp2 sp B. sp2 sp2 C. sp3 sp D. sp3 sp2 13. Diazomethane is a yellow gas that is highly explosive. The structure of diazomethane is shown below. C N +H H NH y x Which of the following shows the correct bond angles, x and y, in diazomethane? angle x angle y A. 120o 120o B. 120o 180o C. 107o 120o D. 107o 180o 14. The reaction between aqueous sodium thiosulfate and dilute acid is found to be first order with respect to acid at low concentration of acid, but zero order with respect to acid when the acid concentration is high. Which graph shows the experimental results? x y

7 15. The rate equation for the gaseous reaction, 2X (g) + Y (g) → Z (g), is given as, Rate = k [X]2[Y]0 If the pressure in the reaction vessel is doubled, at constant temperature, by what factor would the rate of reaction increase? A. 2 B. 3 C. 4 D. 8 16. The diagram shows the energy profile diagram of a reaction that occurs with and without catalyst. Which of the following can be deduced from the diagram above? A. E4 is the activation energy for the reverse catalyzed reaction. B. The forward catalyzed reaction is endothemic. C. The enthalpy change of the forward catalyzed reaction is (E2 − E3). D. The enthalpy change of the reverse reaction is decreased by using a catalyst.

8 17. An equilibrium can be represented by the following equation. F (aq) + G (aq) ⇌ 2H (aq) + J (aq) In a certain 1 dm 3 mixture, the equilibrium concentration of G is 10 mol dm −3. What will be the new equilibrium concentration of G if 5 moles of pure G is dissolved in the mixture? A. 15 mol dm−3 B. between 10 mol dm−3 and 15 mol dm−3 C. 10 mol dm−3 D. between 5 mol dm−3 and 10 mol dm−3 18. Which one of the following statements is correct about a chemical reaction for which the equilibrium constant, Kc, is independent of temperature? A. The enthalpy change of the chemical reaction is zero. B. The rate constants of the forward and backward reactions do not vary with temperature. C. There are equal number of moles of reactants and products at equilibrium. D. The forward and backward reactions have the same overall order. 19. The equation below represents a monomer-dimer system at equilibrium. kf 2NO2 (g) ⇌ N2O4 (g) ∆H < 0 brown kb colourless Which statement about the equilibrium is correct? A. kf increases and kb decreases when the equilibrium mixture is heated. B. Increasing the temperature shifts the equilibrium position to the left. C. Decreasing the volume of the system decreases the equilibrium constant, Kc. D. Addition of a catalyst will increase the colour intensity of the mixture.

9 20. The equilibrium constant for reaction I is K. What is the equilibrium constant for reaction II? reaction I SO2 (g) + ½ O2 (g) ⇌ SO3 (g) reaction II 2SO3 (g) ⇌ 2SO2 (g) + O2 (g) A. K −2 B. K 2 C. 2K D. 2K −1 21. Gas A decomposes to two other gases, B and C, according to the following equation: 2A (g) ⇌ 3B (g) + C (g) The graph below shows the decomposition of 1.0 mole of pure gas A with time at various temperatures. Which one of the following statements about the above system is incorrect? A. The decomposition of gas A is endothermic. B. The Kc of the system decreases with increasing temperature. C. The percentage decomposition of gas A is 60% at 300 oC. D. The entropy of the system increases until it reaches a state of equilibrium. 1.0