2018 C1 Promotional Exam Paper 1

This question booklet consists of 12 printed pages. HWA CHONG INSTITUTION C1 Promotional Examination Higher 2 NAME CT GROUP 18S CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet. 9729/01 2 October 2018 40 min READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Complete the information on the optical mark sheet (OMS) as shown below. There are twenty 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 OMS. 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 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 1 1 The graph shows the first ionisation energies of five consecutive elements in the Periodic Table. Which group does D belong to? A 2 B 14 C 15 D 18 2 Semiconductors are widely used in electronic devices. An element can be a semiconductor if it meets the following criteria: • One of its electronic levels is fully occupied (such as an s subshell) • The level immediately above this level is of only slightly higher energy, and is empty or partially filled (such as a p subshell) On this basis, which elements are expected to be semiconductors? 1 31Ga 2 34Se 3 55Cs A 1 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 ABCDE first IE / kJ mol–1

3 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 1 3 In which pair does species I have a smaller bond angle than species II? I II A NO3– NO2– B ClF4– SF6 C XeF4 BrF5 D BrO3– ClO3– 4 Which pair of compounds is arranged in the correct order of relative boiling points? Lower boiling point Higher boiling point A B CH3CH2OH C CH3CH2OH D

4 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 1 5 Carbon forms double bonds with each of the three elements oxygen, sulfur and selenium. In each case, the double bond is polar. In the linear molecules, carbon dioxide, carbonyl sulfide (COS) and carbonyl selenide (COSe), the polarities of these double bonds do not necessarily cancel. Overall polarity of molecule O=C=O 0 O=C=S 0.71 O=C=Se 0.73 Which factors could account for these observations? 1 The C=S bond is more polar than the C=Se bond. 2 The C=O bond is more polar than the C=S bond. 3 The C=Se bond is more polar than the C=O bond. A 1 only B 1 and 2 only C 1 and 3 only D 2 and 3 only

5 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 1 7 The amount of urea present in urine can be determined by measuring the volume of gases liberated when urea is treated with excess nitrous acid. NH2CONH2 + 2HNO2 ® CO2 + 2N2 + 3H2O 0.150 g of urea was treated with excess nitrous acid, and the gas produced was passed through aqueous NaOH. What is the volume of the gas at room temperature and pressure after passing through aqueous NaOH? A 60 cm3 B 120 cm3 C 180 cm3 D 300 cm3 6 Each of the following graphs represents plots for an ideal gas at two different temperatures. Which graph shows the correct relationship where temperature T1 is lower than T2? A B C D T1 T2 n constant pV p V n p 1/V p n constant T1 T2 V p constant n constant T1 T2 T2 T1

6 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 1 8 Isotopic abundances vary greatly depending on the sample that is analyzed. The molar mass of isotopically pure 106Pd is precisely 105.903 g mol–1. However, in one sample of palladium, the molar mass of the sample was found to be 106.003 g mol–1. Which isotope, present in this sample, caused this discrepancy? A 108Pd B 105Pd C 104Pd D 102Pd 9 Ethanol can be formed from ethanal by reduction using hydrogen gas and nickel. The enthalpy changes of combustion, DHoc, of the reactants and product of this reaction are shown below. (g) H2(g) CH3CH2OH(g) DHoc / kJ mol–1 –1167 –286 –1367 Which of the following statements are correct? 1 This reaction is spontaneous at high temperatures. 2 The standard enthalpy change of reaction is –86 kJ mol–1. 3 Nickel acts as a heterogeneous catalyst for this reaction. 4 will be reduced to form under the same conditions. A 2 and 3 only B 1, 2 and 3 only C 2, 3 and 4 only D All are correct (g) + H2(g) → CH3CH2OH(g)

7 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 1 10 Which of the following reactions has a negative DS? A Heating solid calcium carbonate. B Sublimation of solid carbon dioxide. C Rusting of an iron bar to form iron(III) oxide. D Reaction between aqueous sodium hydroxide and aqueous ammonium chloride. 11 The reaction of acidified aqueous potassium iodide with aqueous hydrogen peroxide: 2I–(aq) + H2O2(aq) + 2H+(aq) → I2(aq) + 2H2O(l) is thought to involve the following steps: step 1: H2O2 + I– → H2O + OI– (slow) step 2: OI– + H+ → HOI step 3: HOI + H+ + I – → I2 + H2O Which of the following conclusions can be drawn from this information? 1 The acid is acting as a catalyst. 2 OI– and HOI are intermediates. 3 Step 2 has a lower activation energy than step 1. 4 The reaction is overall second order. A 1 and 2 only B 2 and 3 only C 1 and 3 only D 2, 3 and 4 only

8 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 1 12 The following data were obtained from studies of the reaction between NO and O2 in a vessel at constant temperature. Experiment I II III IV Total initial pressure / atm 1.00 1.60 2.00 x Initial pressure of NO / atm 0.40 0.40 0.80 0.20 Initial rate of reaction / atm s−1 1.08 2.16 8.64 1.08 Which of the following statements is correct regarding the above system? A The reaction is first order with respect to NO. B The rate equation is rate = kPNO2. C The rate constant k has units of atm−2 s−1. D The value of x in the table above is 2.40. 13 The water-gas shift reaction is an industrially important source of hydrogen gas because of the low cost of the reactants. The reactants and products of this reaction exist in an equilibrium that is shown below. CO(g) + H2O(g) = CO2(g) + H2(g) DH = –41 kJ mol–1 Which of the following graphs based on the water-gas shift reaction, are correct? 1 2 3 A 1 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3

9 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 1 14 Two gases, P and Q, react as follows. P (g) + 3Q (g) = PQ3 (g) A system containing, P, Q and PQ3 is allowed to reach equilibrium in a 5 dm3 vessel at a temperature of 1000 K. The diagram shows the change in the amount of PQ3 and Q with time. Given that the initial amount of P was 0.2 mol, what is the value of the equilibrium constant KC for this reaction? A B C D 3(0.2)0.1 0.5 ´ 3 3 (0.2)0.1 50.5 ´ ´ 3(0.2)0.2 0.5 ´ 3 3 (0.2)0.2 50.5 ´ ´

10 2018 HCI C1 H2 Chemistry Promotional Exam / Paper 1 The structures of chlorogenic acid and cryptochlorogenic acid are relevant for Q15 and Q16. 15 Chlorogenic acid occurs naturally in coffee and an edible species of bamboo. Cryptochlorogenic acid is an isomer of chlorogenic acid, but is far less common in everyday food. Which functional group is absent in both chlorogenic acid and cryptochlorogenic acid? A alkene B alcohol C carboxylic acid D ketone 16 Which of the following statements about chlorogenic acid and cryptochlorogenic acid is incorrect? A Chlorogenic acid has 32 stereoisomers. B Cryptochlorogenic acid contains four sp2 hybridized carbon atoms. C Chlorogenic acid and cryptochlorogenic acid are constitutional isomers. D Chlorogenic ac