HCI Prelim P1 QP

This document consists of 12 printed pages. HWA CHONG INSTITUTION C2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 16S CENTRE NUMBER INDEX NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 20 September 2017 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Complete the information on the Answer Sheet as shown below. There are 30 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 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.

© Hwa Chong Institution 2017 9729 / 01 / C2 Prelim 2017 2 1 Why is the second ionisation energy of sodium higher than that of magnesium? A Magnesium has more protons than sodium. B Sodium has a complete octet, but magnesium does not. C The ionic radius of Na+ ion is larger than that of Mg+ ion. D The electron to be removed from sodium is closer to the nucleus. 2 Use of the Data Booklet is relevant to this question. A mass of 0.457 g of solid carbon dioxide was vapourised into an evacuated gas syringe at r.t.p. A small amount of inert gas was introduced into the gas syringe and the volume of the gas syringe was 334.5 cm3. The temperature was kept constant throughout. How much inert gas was introduced into the gas syringe? A 1.4  10–2 mol B 3.3  10–3 mol C 3.5  10–3 mol D 4.3  10–3 mol 3 Propadiene and propyne both have the same molecular formula, C 3H4. They exist in equilibrium as shown: H2C=C=CH2 ⇌ CH3CCH propadiene propyne Which bond is present in propadiene but not present in propyne? A a  bond formed by 1s – 2sp overlap B a  bond formed by 2p – 2p overlap C a  bond formed by 2sp – 2sp2 overlap D a  bond formed by 2sp2 – 2sp2 overlap

© Hwa Chong Institution 2017 9729 / 01 / C2 Prelim 2017 3 4 Which molecules contain a 90º bond angle? 1 SF6 2 PCl5 3 XeF4 4 SiCl4 A 1, 2, 3 and 4 B 1, 2 and 3 only C 1 and 2 only D 3 and 4 only 5 When T l+(aq) ions are reacted with VO 3–(aq) ions, T l3+(aq) ions and V 2+(aq) ions are formed. Assuming the reaction goes to completion, how many moles of Tl+(aq) and VO3–(aq) would result in a mixture containing equal number of moles of VO 3–(aq) and V 2+(aq) once the reaction had taken place? moles of Tl+(aq) moles of VO3–(aq) A 1 2 B 1 3 C 3 2 D 3 4 6 Compound G is produced by actinobacteria in the soil and is responsible for the “it just rained” smell. How many moles of oxygen gas are needed to completely burn 1 mole of compound G? A 16.75 B 17.00 C 17.25 D 17.50

© Hwa Chong Institution 2017 9729 / 01 / C2 Prelim 2017 4 7 Which of the following changes will result in an increase in entropy? A forward reaction of [Fe(H2O)6]2+(aq) + edta4–(aq) ⇌ [Fe(edta)]2–(aq) + 6H2O(l) B mixing of 1 mol of N2 with 1 mol of Ar at constant volume and temperature C cooling of liquid ethanol from 50 oC to 20 oC D condensation of water vapour 8 Which equation correctly represents both the enthalpy change of combustion, ∆Hc, and the enthalpy change of formation, ∆Hf, of the respective species? ∆Hc ∆Hf equation 1 Na(s) Na2O(s) 2Na(s) + ½O2(g) → Na2O(s) 2 C(s) CO2(g) C(s) + O2(g) → CO2(g) 3 H2(g) H2O(l) H2(g) + ½O2(g) → H2O(l) A 1 and 2 only B 2 and 3 only C 2 only D 1, 2 and 3 9 The mechanism below has been proposed for the reaction between CHCl3 and Cl2. Step 1: Cl2(g) ⇌ 2Cl(g) fast Step 2: Cl(g) + CHCl3(g) → CCl3(g) + HCl(g) slow Step 3: CCl3(g) + Cl(g) → CCl4(g) fast Which rate equation is consistent with this mechanism? A rate = k[CHCl3]1 [Cl]1 B rate = k[CHCl3]1 [Cl2]1 C rate = k[CHCl3]1 [Cl2]½ D rate = k[Cl2]1

© Hwa Chong Institution 2017 9729 / 01 / C2 Prelim 2017 5 10 Iodine–131 is a radioactive isotope with a half -life of 8 days. Given that radioactive decay is a first-order reaction, what fraction of the isotope would remain after 80 days? A 1 20 B 1 160 C 1 28 D 1 210 11 The enthalpy change of reaction for the conversion of sulfur dioxide to sulfur trioxide is shown below. 2SO2 (g) + O2 (g) ⇌ 2SO3 (g) ∆H = –196 kJ mol–1 Which of the following statements is correct? A When the volum e of the system increases at constant temperature , the yield of SO3 increases. B When a catalyst is introduced to the system, the yield of SO3 increases. C The forward reaction is spontaneous at all temperatures. D When the temperature is increased, Kc decreases. 12 Which of the following silver compounds would give the highest concentration of silver ions in its saturated solution? compound magnitude of solubility product A AgCN 6  10–17 B AgSCN 1  10–12 C Ag2SO3 2  10–14 D Ag3PO4 9  10–17 13 Which of the following is a satisfactory indicator for the titration of 0.1 mol dm –3 methylamine and 0.1 mol dm–3 hydrochloric acid? A methyl red (pH range 4.2 – 6.3) B bromothymol blue (pH range 6.0 – 7.6) C phenolphthalein (pH range 8.2 – 10.0) D There is no satisfactory indicator.

© Hwa Chong Institution 2017 9729 / 01 / C2 Prelim 2017 6 14 Triglycerides are the main constituents of body fat in humans and animals. The diagram shows the structure of a triglyceride. What is the total number of stereoisomers possible for this triglyceride? A 21 B 23 C 24 D 25 15 When heated with chlorine, the following hydrocarbon undergoes free radical substitution. In the propagation step, the free radical Q• is formed by the loss of one hydrogen atom. Ignoring any stereoisomers, how many different forms of Q• are theoretically possible? A 3 B 4 C 6 D 8 16 Compound W is heated with excess acidified KMnO4 for a prolonged period. compound W Which of the following compounds is least likely to be a product of this reaction? A CO2 C B D

© Hwa Chong Institution 2017 9729 / 01 / C2 Prelim 2017 7 17 Liquid bromine is added separately to the following pairs of compounds under various conditions. Which of the following pairs of compounds will give the same observations? A Benzene and phenol, in the presence of uv light. B Hexane and methylbenzene, in the presence of uv light. C Pentene and pentane, in the absence of uv light. D Phenylamine and benzene, in the absence of uv light. 18 Enantiomeric excess is the measure of the excess of one enantiomer over another in a mixture. Consider a pair of enantiomers, R and S. If the R enantiomer makes up 75% of the mixture while the S enantiomer makes up 25% of the mixture, R has an enantiomeric excess of 50%. Which of the following reactions would result in a mixture which gives an enantiomeric excess of 0%? 1 2 3 A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3

© Hwa Chong Institution 2017 9729 / 01 / C2 Prelim 2017 8 19 What will be produced when the following compound is reacted with cold NaOH(aq)? A C B D 20 Diadzein belongs to a class of compounds known as isoflavenoids, and is a major component of soya beans. Which statement about diadzein is not correct? A When diadzein reacts with aqueous Br2, the product contains chiral centres. B When heated with ethanoic acid and concentrated sulfuric acid, diadzein forms an ester. C When neutral FeCl3 is added to diadzein, a purple colouration is observed. D When 2,4-DNPH is added to diadzein, an orange precipi