2022 EJC Prelims Paper 1 QP

© EJC [Turn Over EUNOIA JUNIOR COLLEGE JC2 Preliminary Examination 2022 General Certificate of Education Advanced Level Higher 2 CHEMISTRY Paper 1 Multiple Choice 9729/01 22 September 2022 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, civics group and registration number on the Answer Sheet in the spaces provided unless this has been done for you. 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 question paper. The use of an approved scientific calculator is expected, where appropriate. This document consists of 12 printed pages.

2 © EJC 9729/01/J2Prelims/22 1 The hardness present in a water sample due to dissolved calcium ions can be determined by using an ion-exchange column. A 50 cm 3 sample of a solution containing calcium sulfate was passed through the ion - exchange resin. The calcium ions in the sample were quantitatively exchanged by hydrogen ions. The sample collected after passing through the resin required 25 cm 3 of 1.0 × 10−2 mol dm−3 potassium hydroxide for complete neutralisation. What was the concentration of the calcium sulfate in the original sample? A 2.5 × 10−3 mol dm−3 B 5.0 × 10−3 mol dm−3 C 2.0 × 10−2 mol dm−3 D 1.0 × 10−2 mol dm−3 2 Use of the Data Booklet is relevant to this question. The table below shows the fifth, sixth, seventh, eighth and ninth ionisation energies of an element, which is either in the third or fourth period. 5th 6th 7th 8th 9th ionisation energy / kJ mol–1 6 500 9 400 11 000 33 600 38 600 Which element has these ionisation energy values? A As B Se C Cl D Ar 3 Bromine trifluoride is a liquid which undergoes auto -ionisation at room temperature as represented by the following equation: 2BrF 3  BrF + 2 + BrF ― 4 Which of the following is correct regarding BrF 3, BrF + 2 and BrF ― 4 ? A BrF 3 is planar while BrF ― 4 is non-planar. B BrF + 2 is linear while BrF ― 4 is tetrahedral in shape. C The F–Br–F bond angle in BrF 3 is smaller than that in BrF ― 4 . D There are more lone pairs of electrons around the Br atom in BrF 3 than that in BrF + 2 .

3 © EJC 9729/01/J2Prelims/22 [Turn over 4 E and F are both ideal gases, and the relative molecular mass of E is half that of F. Which graph is obtained when pV is plotted against T for equal masses of the two gases? A B C D 5 Changes in temperature can affect the spontaneity of a reaction. Which statements are correct? 1 If a reaction is endothermic and has a negative entropy change, the reaction is spontaneous at all temperatures. 2 If a reaction is exothermic and has a negative entropy change, the reaction is non-spontaneous at all temperatures. 3 If a reaction is exothermic and has a positive entropy change, the reaction is spontaneous at all temperatures. A 1 and 3 B 1 only C 2 only D 3 only 6 Which equation does not correspond to the enthalpy change stated? A CH3CO2H(aq) + KOH(aq) → CH3CO2K(aq) + H2O(l) neutralisationH B Na+(g) + H+(g) + CO 2– 3 (g) → NaHCO3(s) lattice energyH ( )( )3NaHCO s C NaHSO4(s) + aq → Na+(aq) + H+(aq) + SO 2– 4 (aq) solutionH ( )( )4NaHSO s D S(s) + 4H2(g) + N2(g) + 2O2(g) → (NH4)2SO4(s) formationH ( )( )4 2 4(NH ) SO s pV T E F 293 K pV T E F 293 K pV T E F 293 K pV T E F 293 K

4 © EJC 9729/01/J2Prelims/22 7 The mechanism for the acid-catalysed reaction between CH3COCH3 and I2 is given. Which statements are correct for the reaction? 1 At low pH, the reaction is observed to be pseudo-first order. 2 The rate constant increases as pH decreases. 3 The rate of reaction is independent of [I2]. A 1 only B 3 only C 1 and 2 only D 1 and 3 only 8 Known amount of hydrogen and iodine are allowed to come to equilibrium at 500 oC in a vessel of known volume. H2 + I2  2HI From which experimental method can Kc be found? A Measuring the total pressure in the vessel. B Slow cooling to 20 ºC, breaking open the vessel under aqueous potassium iodide, and titrating the iodine present with aqueous sodium thiosulfate. C Rapid cooling to 20 ºC, breaking open the vessel under aqueous potassium iodide, and titrating the iodine present with aqueous sodium thiosulfate. D Withdrawal of a measured sample of the equilibrium mixture, followed by complete decomposition of the hydrogen iodide present, and then titrating the total amount of iodine with aqueous sodium thiosulfate.

5 © EJC 9729/01/J2Prelims/22 [Turn over 9 Consider the following equilibrium for the adsorption of gas G on the active sites of a metal catalyst, M: ( ) ( ) ( ) 1 2 g s s k k +G M GM H  0 where k1 is the rate constant for the adsorption, and k2 is the rate constant for the desorption. The percentage occupancy, , of metal surface by gas G can be represented as: 1 2 1 2 1 k pk k pk = + G G where pG is the partial pressure of gas G. Which of the following statements is correct regarding the above system? A Kp of the system increases with increasing temperature. B Kp of the system is equal to its Kc. C The greater the total surface area of the metal catalyst , the greater the percentage occupancy, , of the metal surface by gas G. D At high pressures of gas G, increasing the temperature does not increase the percentage occupancy, , of the metal surface by gas G. 10 Which of the following titration curves is obtained when HCl(aq) is titrated against standard Na2CO3(aq)? A B C D pH volume of titrant 0 pH volume of titrant 0 pH volume of titrant 0 pH volume of titrant 0

6 © EJC 9729/01/J2Prelims/22 11 A solution of cysteine in its fully protonated form is titrated against a standard solution of potassium hydroxide. The structure of fully protonated cysteine is shown below and its three pKa values are 10.3 (for –SH), 8.1 and 1.9. The isoelectric point is the pH value at which the net electric charge of a molecule is zero, and in the case of cysteine, can be estimated by taking the average of two appropriate pKa values. Which of the following indicators can be used to detect the isoelectric point of cysteine? indicator working range A methyl orange 3.2 – 4.4 B methyl red 4.1 – 6.1 C bromothymol blue 6.0 – 8.0 D phenol red 6.9 – 8.9 12 Silver ions can be used as an alternative disinfecting agent for public swimming pools. The Ag+ concentration needs to be between 1.0 × 10–7 mol dm–3 and 1.0 × 10–6 mol dm–3 for effective disinfection. Saturated solutions of four different compounds were prepared by stirring an excess of each compound in pure water. Which of the following compounds would provide the necessary silver ion concentration required for disinfection? compound Ksp A Ag2CO3 8.1 × 10–12 B AgCl 1.8 × 10–10 C AgBr 5.4 × 10–13 D AgIO3 3.2 × 10–8

7 © EJC 9729/01/J2Prelims/22 [Turn over 13 L is a substance made from two Period 3 elements. When L is added to cold water, a vigorous reaction occurs and a suspension consisting of a white solid in a colourless solution is formed. Upon filtration of this suspension, the residue is found to be insoluble in water and sulfuric acid . When zinc metal is added to the filtrate, effervescence is observed. Which two Period 3 elements could L be made of? A Mg and Cl B Si and Cl C Mg and Si D Al and Si 14 The metals of Group 2, magnesium to ba