NYJC 2023 H2 Chemistry 9729 P1

[Turn Over This document consists of 19 printed pages. NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 21 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, CT and NRIC / FIN on the Answer Sheet in the spaces provided. There are thirty questions in 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.

2 H2 Chemistry 9729/01 NYJC J2/2023 PRELIM 1 When Tl+(aq) ions are reacted with VO3 –(aq) ions, Tln+(aq) ions and V2+(aq) ions are formed. Assuming the reaction goes to completion, 3 mol of T l+(aq) and 4 mol of VO3 –(aq) would result in a mixture containing equal number of moles of VO3 –(aq) and V2+(aq). What is the value of n? A 2 B 1 3 C 4 D 5 2 Two elements E and G have the following properties.  E and G form ionic compounds Na2E and Na2G with sodium respectively.  When reacted with fluorine, only GF6 is formed but not EF6. Which pair of electronic configurations of E and G is correct? E G A [He]2s22p4 [Ne]3s23p4 B [He]2s22p2 [Ne]3s23p4 C [Ne]3s23p4 [He]2s22p4 D [Ne]3s23p4 [He]2s22p2

3 H2 Chemistry 9729/01 NYJC J2/2023 PRELIM [Turn Over 3 A compound with an unknown central atom J has the following shape. J O 107 o Cl Cl Which of the statements are correct about this compound? 1 There are 3 bond pairs and 1 lone pair around the central atom J. 2 There are a total of 10 electrons around the central atom J. 3 Element J is in Group 15 of the Periodic Table. 4 Element J is less electronegative than oxygen. A 1 and 2 only B 2, 3 and 4 only C 1, 2 and 4 only D 1, 3, and 4 only 4 BF3 reacts with (CH3)3N to give (CH3)3NBF3. Which statement is correct? A (CH3)3NBF3 contains hydrogen bonds. B The B atom in (CH3)3NBF3 is not electron deficient. C (CH3)3N is the Lewis acid while BF3 is the Lewis base. D N and B atoms in (CH3)3NBF3 are trigonal pyramidal and trigonal planar in shape respectively.

4 H2 Chemistry 9729/01 NYJC J2/2023 PRELIM 5 A given mass of a diatomic gas was placed in a vessel of fixed volume V cm3 at a pressure p atm and temperature T C. Assuming ideal behaviour, which of the following changes would cause the density of the gas to double? A Cooling the gas to ½ T C. B Adding a catalyst that causes the gas to dissociate into gaseous atoms at T C. C Adding an equal mass of the same gas into the same vessel at T C. D Connecting the vessel to an identical vessel containing the same mass of the diatomic gas at T C and p atm.

5 H2 Chemistry 9729/01 NYJC J2/2023 PRELIM [Turn Over 6 Use of the Data Booklet is relevant to this question. An experiment was conducted to determine the efficiency of the heating of a can of water using a spirit burner. You are given the following data: change in temperature of water = 15 oC relative molecular mass of ethanol = 46.0 enthalpy change of combustion of ethanol = –1371 kJ mol−1 specific heat capacity of water = 4.18 J g−1 K−1 The efficiency of this heating process is 70%. W hich expression below gives the mass of ethanol burnt? A 1 1 1 1 1 1 B 1 1 1 1 1 1 C 1 1 1 1 1 1 D 1 1 1 1 1 1 burner containing ethanol can containing 300 g of water thermometer

6 H2 Chemistry 9729/01 NYJC J2/2023 PRELIM 7 Hydrogen peroxide decomposes to form water and oxygen gas as shown in reaction 1. reaction 1 2H2O2(l)  2H2O(l) + O2(g) Given the following data at 298 K, reaction 2 O2(g) + 2H2(g)  2H2O(l) ΔH2 o = a kJ mol–1; ΔS2 o = b J mol–1 K–1 reaction 3 O2(g) + H2(g)  H2O2(l) ΔH3 o = c kJ mol–1; ΔS3 o = d J mol–1 K–1 what is the value of ΔGo, in kJ mol–1, for reaction 1 at 298 K? A (a – c) – 298(b − d) B (a – 2c) – 298(b – 2d) C (a – c) – 0.298(b − d) D (a – 2c) – 0.298(b – 2d)

7 H2 Chemistry 9729/01 NYJC J2/2023 PRELIM [Turn Over 8 A student performed an experiment to investigate a hypothetical reaction. 2K + L  M The graph of [K] against time for the experiment is plotted below. Given that the units for the rate constant is mol1 dm3 min1, which statement is correct? A The reaction is elementary. B The gradient of tangent at t = 0 min increases by four times when initial [L] doubles. C The half-life of the reaction remains constant when a catalyst is added. D The half-life of this experiment remains constant when initial [ K] doubles but halved when initial [L] doubles. 20 0.0500 [K] t / min 0.0250 0.0125 40 0

8 H2 Chemistry 9729/01 NYJC J2/2023 PRELIM 9 Use of the Data Booklet is relevant to this question. A student investigated the reaction between iodide ions and peroxydisulfate ions. 2I(aq) + S2O8 2(aq)  I2(aq) + 2SO4 2(aq) In the first experiment, he added Fe3+(aq) as catalyst. In the second experiment , he conducted the experiment under the same conditions but modified the experiment at t1. The graphs of [I2] against time for both experiments are shown below. Which statements are correct? 1 The rate of reaction at any given instant can be obtained from the graph. 2 Fe3+(aq) is used as a catalyst as it is able to exhibit variable oxidation states. 3 AgNO3 could have been added at t1. 4 The Boltzmann distribution graph for the first experiment is as follows. A 1 and 2 only B 1 and 4 only C 1, 2 and 3 only D 2, 3, and 4 only [I2] first experiment time / min t1 second experiment kinetic energy number of particles Ea (catalysed)

9 H2 Chemistry 9729/01 NYJC J2/2023 PRELIM [Turn Over 10 2.0 mol of NO 2 dimerises to form N2O4. The reaction was carried out in a 1 dm 3 sealed tube. The graph below shows the Gibbs free energy change during the reaction. 2NO2(g) ⇌ N2O4(g) H o = x kJ mol−1 Which statements are correct? 1 H o has a negative value. 2 The equilibrium constant, Kc, is 1.66 mol−1 dm3. 3 The forward reaction is more spontaneous at low temperature. 4 When the reaction is repeated under the same conditions with 0.3 mol of NO 2 and 0.85 mol of N2O4 in 1 dm3 sealed tube, the position of equilibrium shifts to the right. A 1 and 3 only B 1, 2 and 3 only C 2, 3 and 4 only D 1, 2, 3 and 4

10 H2 Chemistry 9729/01 NYJC J2/2023 PRELIM 11 When 25 cm 3 of aqueous HC l is titrated against aqueous CH 3CH2NH2 of the same concentration, the following pH curve was obtained. At which point will the mixture achieve maximum buffering capacity? 12 The pH of pure water is 6.88 at 32 C. The pH of a saturated solution of a Group 2 hydroxide is 11.70 at the same temperature. What is the value of the solubility product of this hydroxide at 32 C? A 6.3 x 10–8 B 3.3 x 10–7 C 1.3 x 10–5 D 3.8 x 10–5