2023 SOTA Yr 6 Chem HL Prelim Exam P1

Yr6/4/CHEM/HP1/Aug2023 17 pages © School of the Arts, Singapore CHEMISTRY Higher Level Paper 1 Preliminary Examinations Tuesday 29 August 2023 1 hour INSTRUCTIONS TO CANDIDATES • Write your name, class and index number in the blanks below. • Do not open this examination paper until instructed to do so. • Answer all the questions. • For each question, choose the answer you consider to be the best and indicate your choice on the answer sheet provided. • The periodic table is provided for reference on page 2 of this examination paper. • The maximum mark for this examination paper is [40 marks]. Name: Class: Index: 40

- 2 - Yr6/4/CHEM/HP1/Aug2023 The periodic table

- 3 - Yr6/4/CHEM/HP1/Aug2023 Turn Over 1. What is the sum of coefficients when the following equation is balanced using the smallest whole number? ….Fe2+ + ….Cr2O72− + ….H+ → ….Fe3+ + ….Cr3+ + ….H2O A. 26 B. 28 C. 31 D. 36 2. What is the final concentration, in mol dm-3, of hydrochloric acid when 200 cm3 of 0.100 mol dm-3 hydrochloric acid is mixed with 300 cm3 0.200 mol dm-3 hydrochloric acid? A. 0.140 B. 0.150 C. 0.160 D. 0.190 3. 2.00 g of an alcohol, when vaporized, has a volume of 426 cm3 at 400 K and 100 kPa. Which equation shows its molar mass in g mol-1? A. 2.00 × 8.31 × 400100 × 426 B. 2.00 × 8.31 × 400 × 106 100 × 426 C. 2.00 × 8.31 × 400 106 × 426 × 100 D. 2.00 × 8.31 × 400 × 106100 × 103 × 426

- 4 - Yr6/4/CHEM/HP1/Aug2023 4. Which of these statements cannot be deduced from the periodic table on page 2? A. Each chromium atom has 28 neutrons. B. There are a few isotopes of neon in nature. C. There are 15 lanthanoids and 15 actinoids. D. The oxides of chlorine are acidic. 5. The first six ionization energies, in kJ mol-1, of an element are given below. IE1 IE2 IE3 IE4 IE5 IE6 578 1816 2744 11 576 14 829 18 375 Which group in the periodic table is this element found? A. Group 2 B. Group 13 C. Group 15 D. Group 16 6. The graph shows a set of data for the elements in period 3. What is the label on the vertical axis of this graph? A. First ionization energy B. Electrical conductivity C. Electronegativity D. Melting point Na Mg Al Si P S Cl Ar

- 5 - Yr6/4/CHEM/HP1/Aug2023 Turn Over 7. Which oxide does not dissolve in water but reacts with an alkali? A. MgO B. SiO2 C. P4O10 D. SO3 8. What is the overall charge, x, of this iron(III) complex? [Fe(H2O)4(OH)2]x A. 3+ B. 1+ C. 1- D. 2- 9. Which combination leads to a strong metallic bond? Charge on the metal ion Radius of ion A. high large B. high small C. low small D. low large 10. Which series shows molecules in order of increasing bond angles? A. NH3 < CH4 < CO2 B. NH3 < CH4 < H2O C. CH4 < BF3 < NH3 D. H2O < CO2 < BF3

- 6 - Yr6/4/CHEM/HP1/Aug2023 12. The diagram shows the structure of ice. [Source: https://johncarlosbaez.wordpress.com/2012/04/15/ice/] Which statement is correct? A. Two electron pairs from each oxygen atom are involved in forming hydrogen bonds. B. London (dispersion) forces and dipole-dipole forces are absent in ice. C. All bond angles surrounding each oxygen atom is 120°. D. The structure makes ice denser than water. 11. Diamond, graphite and buckminsterfullerene are three allotropes of carbon. Which statement is correct for all three allotropes? A. s bonds are present in all of them. B. Bond angles of 120° are present in all of them. C. Delocalized electrons are present in all of them. D. All of them have giant covalent lattice structures. Oxygen Hydrogen Hydrogen bonds

- 7 - Yr6/4/CHEM/HP1/Aug2023 Turn Over 13. Which diagram represents the shape of a sp hybridized orbital? A. B. C. D. 14. Which processes are exothermic? I. Freezing II. Melting III. Condensation A. I and II only B. I and III only C. II and III only D. I, II and III 15. Which equation represents the average bond enthalpy of a O–H bond? A. !"H2O (g) → H (g) + !"O (g) B. H2O (g) → H2 (g) + !"O2 (g) C. H2 (g) + !"O2 (g) → H2O (l) D. 2H (g) + !"O2 (g) → H2O (l)

- 8 - Yr6/4/CHEM/HP1/Aug2023 16. Consider the following enthalpy of combustion data. C (s) + O2 (g) → CO2 (g) ΔH = x kJ mol–1 H2 (g) + !"O2 (g) → H2O (l) ΔH = y kJ mol–1 C2H6 (g) + #"O2 (g) → 2CO2 (g) + 3H2O (l) ΔH = z kJ mol–1 What is the enthalpy of formation of ethane in kJ mol–1? 2C (s) + 3H2 (g) → C2H6 (g) A. x + y – z B. z – x – y C. z − 2x −3y D. 2x + 3y – z 17. Which reaction shows the largest increase in entropy? A. 2KOH (aq) + FeSO4 (aq) → K2SO4 (aq) + Fe(OH)2 (s) B. C2H4 (g) + 3O2 (g) → 2CO2 (g) + 2H2O (g) C. MgSO3 (s) → MgO (s) + SO2 (g) D. (NH4)2Cr2O7 (s) → Cr2O3 (s) + N2 (g) + 4H2O (g) 18. Which statements describe the effects of adding a catalyst and increasing the temperature on the rate of a reaction? Adding a catalyst Increasing the temperature A. collision frequency increases collision frequency increases B. activation energy decreases collision frequency increases C. collision frequency increases activation energy increases D. activation energy increases activation energy decreases

- 9 - Yr6/4/CHEM/HP1/Aug2023 Turn Over 19. The rate expression for the reaction P + Q à R + S is rate = k[Q] . Which statement is correct for the reaction? A. Q is a catalyst in this reaction. B. The concentration of P does not change during the reaction. C. The rate of reaction is not affected by the concentration of P. D. The concentration of Q decreases linearly as the reaction progresses. 20. Consider the following reaction. NO2(g) + CO(g) à NO(g) + CO2(g) At T < 227 oC, the rate expression is rate = k [NO2]2. Which of these mechanisms is consistent with the rate expression? A. NO2 + NO2 ⇌ N2O4 fast N2O4 + 2CO à 2NO + 2CO2 slow B. NO2 + CO à NO + CO2 slow C. NO2 à NO + O slow CO + O à CO2 fast D. NO2 + NO2 à NO3 + NO slow NO3 + CO à NO2 + CO2 fast 21. The exothermic reaction I2 (g) + 3Cl2 (g) ⇌ 2ICl3 (g) is at equilibrium. Which is correct of the equilibrium constant, Kc, and the position of the equilibrium when temperature is raised at constant volume? Equilibrium constant, Kc Position of equilibrium A. decrease shift towards products B. decrease shift towards reactants C. increase shift towards products D. increase shift towards reactants

- 10 - Yr6/4/CHEM/HP1/Aug2023 22. The equilibrium constant for N2(g) + 3H2(g) ⇌ 2NH3(g) is K. What is the equilibrium constant for this equation 4NH3 (g) ⇌ 2N2(g) + 6H2(g)? A. 1𝐾 B. 12𝐾 C. 1𝐾" D. 12𝐾" 23. Which of the following would shift the equilibrium to the right? [Cu(H2O)6]2+(aq) + 4Cl– (aq) ⇌ [CuCl4]2– (aq) + 6H2O(l) ∆H > 0 I. Increasing the temperature of the solution II. Adding concentrated HCl III. Removing water by evaporation A. I and II only B. I and III only C. II and III only D. I, II and III 24. Equal volumes of 0.10 mol dm-3 butanoic acid and hydrochloric acid were titrated with 0.10 mol dm-3 sodium hydroxide solution. Which of the following is the same for both titrations? A. Initial pH B. Initial electrical conductivity C. Volume of NaOH for complete neutralization D. Heat evolved in the neutralization