ACSI Paper 1 Prelim Suggested Solutions

1 Anglo-Chinese School (Independent) Year 6 PRELIMINARY EXAMINATION 2023 INTERNATIONAL BACCALAUREATE DIPLOMA PROGRAMME CHEMISTRY HIGHER LEVEL PAPER 1 Monday 12 th September 2022 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 18 printed pages, including the cover page.

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3 1. In which of the following species would nitrogen be reduced if converted to N2O4? A. NH 3 B. NO C. NO3− D. NO2− 2. How many electrons are needed when the following half-equation is balanced using the lowest possible whole numbers? __SO2 + __H2O ⟶ ___SO42− + ___H+ + ___e− A. 1 B. 2 C. 3 D. 4 3. Typically, when a person coughs, he first inhales about 2.0 dm3 of air at 1.0 atm and 25 oC. In the lungs, the air is warmed to 37 oC and compressed to a volume of about 1.7 dm3 by the action of the diaphragm and chest muscles. The sudden opening of the vocal cord then releases the air explosively. Just prior to this release, what is the approximate pressure (in atm) of the gas inside the lungs? A. 1.0×2.0×37 25×1.7 B. 1.0×2.0×310 298×1.7 C. 25×1.7 1.0×2.0×37 D. 298×1.7 1.0×2.0×310

4 4. Which of the following statements contains one mole of the stated particle? [At SATP, one mol of gas occupies 24.0 dm3] A. Molecules in 19.00 g of fluorine gas. B. Electrons in 24.0 dm 3 of hydrogen gas at SATP. C. Neutrons in 1.00 g of helium gas. D. Protons in 2.018 g of neon gas. 5. The first eight successive ionization energies for an atom are shown. In which group is the atom found? A. 15 B. 16 C. 17 D. 18

5 6. How many electrons are there in all the d orbitals in a xenon atom? A. 10 B. 18 C. 20 D. 36 7. Which trend is correct across the period? A. Atomic radius decreases B. Electronegativity decreases C. Ionic radius increases D. Melting point decreases 8. Which of the following affects the colour of the complex formed by a particular transition metal? I. Oxidation state of metal II. Type of ligand III. Geometry of the complex A. I and II only B. I and III only C. II and III only D. I, II and III

6 9. Which of the following statements best explains why [Fe(H2O)F5]2- appears colourless? A. The d orbitals are half-filled B. The electrons do not undergo d-d transition. C. The complex is octahedral in shape. D. The energy gap between the d orbitals does not corresponds to radiation from the visible light region. 10. Which of the following correctly show the strongest intermolecular forces of attraction for the compound? Compound Strongest Intermolecular forces of attraction A. CH 3CH2F Hydrogen bonding B. CH2O Dipole forces C. CH2Cl2 London dispersion force D. C 6H5CONH2 Dipole forces 11. Which species does not have resonance structures? A. O 3 B. NO3 C. CH3COCH3 D. CO32

7 12. The structure shows the bonding in salicylic acid. Which statements are correct? I The molecules do not form London dispersion forces between them. II The carbon atom is the carboxyl group is sp2 hybridised. III The molecule can form intramolecular hydrogen bonding. A. I and II only B. I and III only C. II and III only D. All of the above 13. Which of the following compound contains the strongest ionic bond? A. NaBr B. NaC l C. MgF2 D. MgC l2

8 14. A large excess of magnesium ribbon is added to dilute hydrochloric acid and the volume of hydrogen gas produced is measured as the reaction proceeds. The reaction is exothermic. The results are shown. Which explains the changes in the rate of reaction between points P and Q and between points Q and R? Ca C b O c A. sp sp sp 2 B. sp 2 sp 3 sp 2 C. sp 3 sp 3 sp D. sp 2 sp 2 sp between points P and Q between points Q and R the reaction temperature increases the acid concentration decreases magnesium’s surface area decreases the acid concentration decreases the reaction temperature increases the magnesium has been used up magnesium’s surface area decreases the magnesium has been used up 15. When the temperature of a particular reaction is increased by 10 C (e.g. from 20 C to 30 C) the rate of the reaction approximately doubles. What is the most significant reason for this increase? A. A reduced activation energy for the reaction. B. More particles colliding at the energy greater than the activation energy. C. An increased collision frequency of the reactant molecules. D. A different mechanism for the reaction.

9 16. A student mixes 2.50 g of excess zinc powder with 25.0 cm3 of 0.350 mol dm−3 hydrochloric acid. The temperature increases by 3.5 oC. What is the enthalpy change for the reaction, in kJ mol−1? (specific heat capacity of water = 4.18 J g−1 K−1) A. 27.5  4.18  (3.5 + 273)  65.38 2.50  1000 B. 25.0  4.18  3.5 25.0  0.35 C. 25.0  4.18  3.5  65.38 2.50  1000 D. 27.5  4.18  (3.5 + 273) 25.0  0.35 17. Which equation represents the average bond energy of the C–H bond in methane? A. ¼ CH4 (g)  ¼ C (g) + H (g) B. ¼ C (s) + H (g)  ¼ CH4 (g) C. CH4 (g)  C (g) + 4H (g) D. CH4 (g)  CH3 (g) + H (g) 18. The equation on an enthalpy change is shown. 2C (s) + 3H2 (g) + ଻ ଶ O2 (g)  2CO2 (g) + 3H2O (l) Given the following equations, C (s) + O2 (g)  CO2 (g) ΔHo = x kJ H2 (g) + ½ O2 (g) H2O (l) ΔHo = y kJ What is correct expression for the enthalpy change of the reaction above? A. x + y + ΔHco(O2) B. 2x + 3y + ଻ ଶ ΔHco(O2) C. 2 y – 3x D. 3 y + 2x

10 19. Which is correct for a reaction with a negative change in Gibbs free energy, ΔGo? A. The reaction has a negative ΔHo and ΔSo at 298 K. B. The reaction becomes spontaneous at higher temperature. C. The reaction has maximum entropy. D. The formation of product is favoured. 20. In which reaction does entropy increase? A. NaCl (aq) + AgNO3 (aq)  AgCl (s) + NaNO3 (aq) B. H2 (g) + I2 (g)  2HI (g) C. CaCO3 (s)  CaO (s) + CO2 (g) D. H2O (l)  H2O (s) 21. Propanone reacts with iodine in the presence of an acid. CH3COCH3 + I2 CH3COCH2I + HI The mechanism involves the following steps: CH3COCH3 CH3C(OH)=CH2 (slow) CH3C(OH)=CH2 + I2  CH3CI(OH)CH2I (fast) CH3CI(OH)CH2I  CH3COCH2I + HI (fast) Which conclusion cannot be drawn from this information? A. Iodine is not involved in the rate-determining step. B. The acid acts as a catalyst. C. The overall order of the reaction is 3. D. The rate of reaction is not affected by a change in the iodine concentration. H+ H+