CJC 2023 H2 Chem Prelim P1 QP

1 9729/01 CJC JC2 Preliminary Examination 2023 [Turn over CANDIDATE NAME CLASS 2T CHEMISTRY 9729/01 Paper 1 Multiple Choice 15 September 2023 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, class and NRIC/FIN number on the Answer Sheet in the spaces 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 separate Answer Sheet. Read the instructions on the 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 booklet. The use of an approved scientific calculator is expected, where appropriate. This document consists of 16 printed pages. Catholic Junior College JC 2 Preliminary Examinations Higher 2

2 9729/01 CJC JC2 Preliminary Examination 2023 1 What volume of air is required for the complete combustion of 1.0 dm 3 of octane vapour, C8H18(g), in a car engine? (Air contains 20% oxygen by volume.) A 2.5 dm3 B 12.5 dm3 C 62.5 dm3 D 125.0 dm3 2 The ionisation energies, in kJ mol–1, of three elements are given in the table. 1st ionisation energy 2nd ionisation energy 3rd ionisation energy Ne 2080 3950 6150 Na 494 4560 6940 Mg 736 1450 7740 Which statement(s) about these ionisation energies is/are correct? 1 Ne has the greatest 1st ionisation energy of the three elements because its electrons experience the most interelectronic repulsion. 2 Mg has the lowest 2nd ionisation energy of the three elements because the electron being removed experiences the greatest shielding effect. 3 There is a large increase from the 2nd to 3rd ionisation energy of Na because the electron is being removed from the next inner subshell. A 1 and 2 only B 2 only C 1 and 3 only D 3 only 3 Equimolar amounts of the liquids hexane, CH 3(CH2)4CH3, and triethylamine, (CH 3CH2)3N, are mixed together at 20 °C. The original intermolecular forces are disrupted and stronger intermolecular forces between CH3(CH2)4CH3 and (CH3CH2)3N are formed simultaneously. The boiling point of hexane is 69 °C. The boiling point of triethylamine is 90 °C. Which row is correct? initial temperature of mixture boiling point of mixture A above 20 °C below 69 °C B below 20 °C below 69 °C C below 20 °C above 90 °C D above 20 °C above 90 °C

3 9729/01 CJC JC2 Preliminary Examination 2023 [Turn over 4 In the gaseous state, phosphorus(V) chloride exists as a molecule with the formula PCl5. However, when it is a solid, it is ionic with the formula PCl4+PCl6–. Which one of the following statements is correct? A The bond angle in PCl4+ is smaller than that in PCl6–. B There is a dative covalent bond in PCl6–. C The P atom in PCl4+ has an expanded octet. D There is a net dipole moment in PCl5. 5 Which pairs of compounds contain a polar and a non-polar molecule? 1 CO2, H2O 2 SO2, NO2 3 CH2Cl2, SiCl4 A 1, 2 and 3 B 1 and 3 only C 2 and 3 only D 1 only 6 A gaseous dimer, X2, dissociates into its gaseous monomer, X, at 400 K and 1 atm pressure. Dissociation is complete at 450 K. X2 (g) → 2X (g) Which of the following graphs shows the variation of volume with temperature when one mole of X2 is heated from 350 K to 500 K at a constant pressure of 1 atm? Assume that the gases behave ideally. (R = 0.082 mol−1 dm3 atm K−1) A B C D 350 400 450 500 T/ K Vol/ dm3 400R 350 400 450 500 T/ K Vol/ dm3 800R 350 400 450 500 T/ K Vol/ dm3 800R 350 400 450 500 T/ K Vol/ dm3 800R 800R 400R 400R 400R

4 9729/01 CJC JC2 Preliminary Examination 2023 7 Use of the Data Booklet is relevant to this question. At 400 K, the following species behave as ideal gases: H2, CH4, NO2, Ar. 5.00 g of each of these gases is put separately into a gas syringe kept at 400 K. The volume of each gas is adjusted to be the same, and pressure is measured. Which gas will have the lowest pressure? A H2 B CH4 C NO2 D Ar 8 The graph below shows the variation in the melting point for 8 consecutive elements in the Periodic Table, all with atomic number ≤ 20. What can be deduced from the graph? A The ions of A and E are isoelectronic. B The chlorides become less acidic from A to C. C When the oxide of C is added to water, the resulting solution has a pH greater than 7. D The oxide of A reacts with excess aqueous sodium hydroxide to form a soluble complex. 9 Which of the following processes are endothermic? 1 N2(g) + O2(g) → 2NO(g) 2 O‒(g) + e‒ → O2‒(g) 3 C(s) + O2(g) → CO2(g) A 1 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 melting point atomic number

5 9729/01 CJC JC2 Preliminary Examination 2023 [Turn over 10 The graphs below show how the percentage of reactant X(g) in an equilibrium varies with changes in temperature and pressure. Which of the following conclusions about the above equilibrium can be drawn from this information? A The forward reaction is exothermic. B Addition of a catalyst will have a greater effect on the rate of reverse reaction than the rate of forward reaction. C The equation for the reaction could be in the form of W(g) + X(g) ⇌ 2Y(g) + Z(g). D The value of Kc decreases as pressure increases. 11 The rate of removal of a new drug from the body is a first-order reaction. 75% of the initial drug present in a patient is removed over 5.4h. How much time will it take to remove 90% of this drug from the body? A 6.75h B 8.10h C 8.97h D 10.8h temperature pressure %X %X

6 9729/01 CJC JC2 Preliminary Examination 2023 12 The chlorite-tetrathionate reaction, in which the chlorite ion is one of the reactants, has been studied. One of the products, H+(aq), catalyses the reaction. 2S4O62‒ + 7ClO2‒ + 6H2O → 8SO42‒ + 7Cl‒ + 12H+ tetrathionate chlorite Which graph best describes the above reaction? A B C D 13 Metal sulfides are generally insoluble . Ksp values for copper sulfide and zinc sulfide at 298 K are listed in the table below. metal sulfide colour Ksp / mol2dm‒6 CuS black 6.3  10‒36 ZnS white 1.6  10‒24 When aqueous copper sulfate is added to white solid of ZnS, black precipitate of CuS is observed according to the following reaction. ZnS(s) + Cu2+(aq) CuS(s) + Zn2+(aq) What is the equilibrium constant, Kc, for the reaction above? A 1.0  10‒59 B 3.9  10‒12 C 5.0  105 D 2.5  1011 [ClO2‒] rate rate rate time time time

7 9729/01 CJC JC2 Preliminary Examination 2023 [Turn over 14 The graphs below show the variation of two properties of some period 3 elements and/or their compounds. Which of the following correctly describes properties 1 and 2? property 1 property 2 A atomic radius of the elements electrical conductivity of the elements B melting point of the chlorides pH of oxides when added to water C melting point of the elements first ionisation energies of the elements D electrical conductivity of elements pH of chlorides when added to water 15 The structure of vitamin D2 is shown below. When it is completely reacted with hydrogen in the presence of a palladium catalyst at room temperature, how many chiral cen