2022 HCI H2 Chemistry Promo P1 QP

This document consists of 11 printed pages and 1 blank page. HWA CHONG INSTITUTION C1 Promotional Examination Higher 2 CANDIDATE NAME CT GROUP 22S CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 28 September 2022 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 Multiple Choice Answer Sheet 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 separate Answer Sheet. 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 © Hwa Chong Institution 2022 9729/01/C1 Promotional Exam 2022 [Turn over 1 Use of the Data Booklet is relevant to this question. Nuclear theories predict the number of protons and the number of neutrons that give especially stable nuclei. These numbers are known as the nuclear magic numbers. These numbers include 2, 8, 20, 28, 50, 82, 126. The most stable nuclei are the ‘doubly magic’ ones that have a magic number of protons and a magic number of neutrons. Using this theory, which isotope is the most stable? A 2He B 8Be C 40Ca D 210Pb 2 Cyanogen, (CN)2, is a colorless, toxic gas with a pungent smell. N C C N cyanogen Which statements about the cyanogen molecule are correct? 1 It contains two lone pairs of electrons. 2 It contains sp hybridized carbon atoms. 3 It contains a total of four π bonds and two σ bonds. A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1 only

3 © Hwa Chong Institution 2022 9729/01/C1 Promotional Exam 2022 [Turn over 3 In the solid phase, molecules of hydrogen fluoride, HF, are held together by hydrogen bonding in a regular arrangement like water molecules in ice. The bond angle around the F atom is also similar to that around the O atom in ice. However, each HF molecule forms only two hydrogen bonds with neighboring HF molecules in zig- zag chains as shown: Which statement about solid HF is correct? A Solid HF has the same open structure as in ice. B Each hydrogen bond in solid HF is stronger than that in ice. C The bond angle around each F atom is approximately 120°. D The chains form part of a giant covalent structure in solid HF. 4 A flask of fixed volume contains a mixture of nitrogen gas and oxygen gas. Which changes would apply when some helium gas is introduced into the flask at constant temperature? 1 The total pressure of gas in the flask would increase. 2 The mole fractions of nitrogen gas and oxygen gas would decrease. 3 The partial pressures of nitrogen gas and oxygen gas would increase. A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1 only

4 © Hwa Chong Institution 2022 9729/01/C1 Promotional Exam 2022 [Turn over 5 Which statements about empirical and molecular formula are correct? 1 The empirical formula for sodium chloride is NaC l and there is no molecular formula for sodium chloride. 2 H2O represents both the empirical and molecular formula of water. 3 The empirical formula for propene is CH2 while its molecular formula is C3H6. A 1 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 only 6 Use of the Data Booklet is relevant to this question. Which of the following contains the smallest number of particles? A the number of atoms in 15 g of Fe metal B the number of ions in 50 g of solid NaCl C the number of molecules in 15 dm3 of N2 gas at r.t.p D the number of molecules in 10 cm3 of liquid hexane, C6H14 (density = 6.55 g cmˉ3) 7 Which equations do not illustrate the enthalpy changes stated? 1 N(g) + 3H(g) → NH3(g) ∆HꝊformation (NH3) 2 ½Br2(g) → Br(g) ∆HꝊbond energy (Br−Br) 3 Mg(s) → Mg+(g) + eˉ ∆HꝊionisation energy (Mg) A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3

5 © Hwa Chong Institution 2022 9729/01/C1 Promotional Exam 2022 [Turn over 8 Calcium chloride is commonly used to prevent ice formation in cold climates. enthalpy change value in kJ mol−1 lattice energy of CaCl2 −2195 hydration enthalpy of Ca2+ ion −1577 hydration enthalpy of Cl ˉ ion −363 Given the data above, what is the enthalpy change of solution of calcium chloride? A −255 kJ molˉ1 B −108 kJ molˉ1 C +108 kJ molˉ1 D +255 kJ molˉ1 9 The sketch below shows how the entropy of a sample of water varies with temperature. Which statement about the sketch is correct? A The particles are most disordered at point A. B The system is at dynamic equilibrium between points C and D. C Entropy increases at BC because the particles possess greater average kinetic energy. D Entropy increases more at DE compared to at BC because gas particles have a greater degree of disorder compared to liquid particles. C D E B A entropy temperature / K 0 0 T1 T2

6 © Hwa Chong Institution 2022 9729/01/C1 Promotional Exam 2022 [Turn over 10 Which energy profile diagram shows the correct changes when a catalyst is added to a reaction? A B C D 11 242-Curie and 248-Berkelium are radioactive isotopes of man-made elements which have a half-life of 160 days and 320 days respectively. How many days would it take for a sample containing a 4:1 ratio of 242- Curie to 248-Berkelium to decay until the two isotopes are in a 1:1 ratio? A 320 B 480 C 640 D 1280

7 © Hwa Chong Institution 2022 9729/01/C1 Promotional Exam 2022 [Turn over 12 When light is shone for a fixed period into a solution of CH2ICH2I and I2 in CCl4 solvent at 100 oC, the following reaction occurs. CH2ICH2I → CH2=CH2 + I2 experiment relative initial concentration relative light intensity relative initial rate of formation of I2 CH2ICH2I I2 1 2 1 4 2 2 2 1 1 1 3 1 1 4 1 4 1 2 4 1 From the data in the table, the rate of formation of iodine is 1 proportional to �light intensity. 2 independent of initial concentration of I2. 3 proportional to initial concentration of CH2ICH2I. A 1 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3 only 13 A reaction involving P, Q and R is allowed to reach equilibrium with the following equilibrium concentrations: 2P(aq) + Q(aq)   2R(aq) equilibrium concentration / mol dm–3 2.0 1.0 2.0 When 0.5 mol of P was then added to 1 dm 3 of this equilibrium mixture, what will be the new equilibrium concentration, in mol dm–3, for each species? A [P] = 2.5 [Q] = 1.25 [R] = 1.5 B [P] = 2.0 [Q] = 0.75 [R] = 2.5 C 2 < [P] < 2.5 0 < [Q] < 1 2 < [R] < 2.5 D 1.5 < [P] < 2.0 0 < [Q] < 0.5 2.5 < [R] < 3.5

8 © Hwa Chong Institution 2022 9729/01/C1 Promotional Exam 2022 [Turn over 14 The graph below shows how the percentage of a substance, X, produced in an equilibrium mixture varies with pressure at temperatures 298 K and 500 K. Which of the equilibria would X represent the underlined species? A 2NI3(s)   N2(g) + 3I2(g) ∆H = – 290 kJ mol−1 B SO2(g) + ½O2(g)   SO3(g) ∆H = – 198 kJ mol−1 C H2(g) + CO(g)   H2O(g) + C(s) ∆H = + 131 kJ mol−1 D Fe3O4(s) + 4H2(g)   3Fe(s) + 4H2O(g) ∆H = + 151 kJ mol−1 15 Which transformation correctly represents the type of reaction stated?