ACSI 2021 Y6 Prelim Paper 1 QP

1 Anglo-Chinese School (Independent) YEAR 6 PRELIMINARY EXAMINATION 2021 INTERNATIONAL BACCALAUREATE DIPLOMA PROGRAMME CHEMISTRY HIGHER LEVEL PAPER 1 Monday 13th September 2021 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. Shade your Candidate number on the multiple choice 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 17 printed pages, including the cover page.

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3 1. 0.10 mol of sulfuric acid is mixed with 0.10 mol of sodium metal. H2SO4 (aq) + 2Na (s) → Na2SO4 (aq) + H2 (g) Which is correct? Limiting Reagent Maximum yield of H2 /mol A. H2SO4 0.05 B. H2SO4 0.10 C. Na 0.05 D. Na 0.10 2. A 100 cm3 of gas has a pressure of 400 kPa. What would be the new pressure of the gas when the volume of the gas is compressed to half its original volume at constant temperature? A. 100 kPa B. 200 kPa C. 400 kPa D. 800 kPa 3. Which is correct for Se34 79 2– ? protons neutrons electrons A. 34 45 34 B. 34 45 36 C. 36 43 32 D. 79 34 36 4. What is the total number of sub-levels that are occupied in a Cr+ ion? A. 3 B. 4 C. 6 D. 7

4 5. Which statements are correct for the emission spectrum of hydrogen? I. The lines converge at higher frequencies. II. Electron transitions to n = 1 correspond to the ultraviolet region. III. Lines are produced when electrons move from higher to lower energy levels. A. I and II only B. I and III only C. II and III only D. I, II and III 6. Consecutive elements X, Y and Z are in Period 3 of the Periodic Table. Element Y has the highest first ionisation energy and the lowest melting point of these three elements. What are the identities of X, Y and Z? A. Sodium, magnesium, aluminium B. Magnesium, aluminium, silicon C. Aluminium, silicon, phosphorus D. Silicon, phosphorus, sulfur 7. Sulfur is converted to SF6 by fluorine, to SCl2 by chlorine and to S2Br2 by bromine. Which best explains this observation? A. Bond energy of F2 < Cl2 > Br2 B. Oxidising ability of F2 > Cl2 > Br2 C. Electronegativity of F > Cl > Br D. First ionisation energy of F > Cl > Br

5 8. Which complex is colourless in solution? A. [Fe(H2O)6]Cl2 B. [Ni(NH3)6]Cl2 C. [Zn(H2O)6](NO3)2 D. K3[Co(CN)6] 9. Which compound contains both covalent and ionic bonds? A. NH4Cl B. MgBr2 C. CH2Cl2 D. CH3COOH 10. According to VSEPR theory, which molecule would be expected to have the smallest bond angle? A. H2O B. H2CO C. SiH4 D. NH3 11. Which compound is the most soluble in water? A. Methane B. Propane C. Propan-1-ol D. Pentan-1-ol

6 12. Which can exist in both polar and non-polar forms? A. CH2Cl2 B. C2H2Cl2 C. C2HCl3 D. C2H3Cl 13. Which statement about the molecule but-2-yn-1-ol is not correct? A. The centre carbon atoms (2 and 3) are sp hybridised. B. The oxygen atom is sp3 hybridised. C. The terminal carbon atoms (1 and 4) are sp2 hybridised. D. The terminal carbon atoms (1 and 4) have tetrahedral geometry. 14. Using the equations below Cu (s) + 1 2O2 (g) → CuO (s) ∆H = −156 kJ 2Cu (s) + 1 2 O2 (g) → Cu2O (s) ∆H = −170 kJ What is the value of ∆H (in kJ) for the following reaction? 2CuO (s) → Cu2O (s) + 1 2 O2 (g) A. 142 B. 14 C. −14 D. −142 1 2 3 4

7 15. What energy changes occur when chemical bonds are formed and broken? A. Energy is absorbed when bonds are formed and when they are broken. B. Energy is released when bonds are formed and when they are broken. C. Energy is absorbed when bonds are formed and released when they are broken. D. Energy is released when bonds are formed and absorbed when they are broken. 16. Which equation represents the lattice enthalpy of magnesium oxide? A. MgO (s) → Mg (s) + 1 2O2 (g) B. MgO (g) → Mg2+ (g) + O2− (g) C. MgO (s) → Mg2+ (g) + 1 2 O2 (g) D. MgO (s) → Mg2+ (g) + O2− (g) 17. Some chlorine gas is placed in a flask at room temperature and pressure. Which change will cause a decrease in entropy assuming there is no change in temperature and pressure? A. Adding a small amount of hydrogen B. Adding a small amount of ethene C. Adding a small amount of chlorine D. Exposing the flask to sunlight.

8 18. Equal masses of powdered calcium carbonate were added to separate solutions of hydrochloric acid. The calcium carbonate was in excess. The volume of carbon dioxide produced was measured at regular intervals. Which curves best represent the evolution of carbon dioxide against time for the acid solutions shown in the table below? 25 cm3 of 2 mol dm–3 HCl 50 cm3 of 1 mol dm–3 HCl 25 cm3 of 1 mol dm–3 HCl A. I III IV B. I IV III C. I II III D. II I III Volume of CO2 (g) / cm3 time / s I II III IV

9 19. The diagram shows the energy profile for a catalysed and uncatalysed reaction. Which represents the enthalpy change, ∆H, and the activation energy, Ea, for the catalysed reaction? ∆H Ea (catalysed reaction) A. E3 – E4 E1 B. E4 – E3 E2 – E3 C. E4 – E3 E2 D. E4 + E3 E1 – E3 20. Consider the following reaction. NO2 (g) + CO (g) → NO (g) + CO2 (g) At T < 227 °C, the rate expression is rate = k [NO2]2. Which mechanism is consistent with this rate expression? A. NO2 + NO2 ⇌ N2O4 fast N2O4 + 2CO → 2NO + 2CO2 slow B. NO2 + CO → NO + CO2 slow C. NO2 → NO + O slow CO + O → CO2 fast D. NO2 + NO2 → NO3 + NO slow NO3 + CO → NO2 + CO2 fast Potential energy Reaction coordinate E1 E3 E4 E2

10 21. The rate constant, k, is commonly described by the Arrhenius equation: k = A𝑒𝑒−𝐸𝐸𝑎𝑎 𝑅𝑅𝑅𝑅. Which statements are correct? I. A greater Ea value results in a smaller k value. II. The A term takes into account the orientation of the reactants. III. The slope (gradient) of Ink against 1 T equals Ea. A. I and II only B. I and III only C. II and III only D. I, II and III 22. The decomposition of SO3 (g) is a reaction in dynamic equilibrium. 2SO3 (g) ⇌ 2SO2 (g) + O2 (g) What happens when the pressure of the system is increased? A. The rate of forward reaction will decrease and the position of the equilibrium will shift to the left. B. The rate of forward reaction will decrease and the position of the equilibrium will shift to the right. C. The rate of forward reaction will increase and the position of the equilibrium will shift to the left. D. The rate of forward reaction will increase and the position of the equilibrium will shift to the right.