RI 2021 Y5 Timed Practice QP

1 Name: ( ) Class: 22S0______ RAFFLES INSTITUTION 2021 YEAR 5 JULY COMMON TEST Higher 2 CHEMISTRY 9729 2 July 2021 2 hours 15 minutes Additional Materials: Multiple Choice Answer (OMR) Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write your name, index number and civics tutorial group in the spaces provided on the OMR Sheet, and the cover sheets on pages 1 and 15. Do not use staples, paper clips, glue or correction fluid. This paper consists of three sections, A, B and C. Section A (15 marks) Answer this section first. The OMR Sheet will be collected after the first 30 minutes. There are fifteen questions in this section. 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 OMR Sheet. Read the instructions on the OMR 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 the question paper. Section B (30 marks) There are three questions in this section. Answer all questions. Answers to this section are to be written in the spaces provided in the question paper. Section C (35 marks) There are two questions in this section. Answer all questions. Answers to this section are to be written in the spaces provided in the question paper. The use of an approved scientific calculator is expected, where appropriate. This document consists of 24 printed pages. Write in dark blue or black pen. You may use a pencil for any diagrams or graphs. You are reminded of the need for good English and clear presentation in your answers. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s Use Only B1 / 12 B2 / 8 B3 / 10

2 © Raffles Institution 2021 9729/J/21 [Turn Over Section A (15 marks) For each question, there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Use of the Data Booklet is relevant to this question. X and Y are hydrocarbons with the same empirical formula. When 0.1 mol of X and 0.1 mol of Y were combusted together in excess oxygen gas, 39.6 g of CO2 and 16.2 g of H2O were formed. The Mr of Y is two times that of X. Which row gives the correct empirical formula and molecular formula of Y? empirical formula of Y molecular formula of Y A CH C3H3 B CH C6H6 C CH2 C3H6 D CH2 C6H12 2 Under basic conditions, MnO 42− undergoes disproportionation to give two manganese - containing species in the ratio of 2 : 1. One of the species is MnO4−. What could be the other species? A Mn(OH)2 B MnO2 C Mn2O3 D Mn2O7 3 Equal volumes of 1.0 mol dm−3 HCl(aq) and 1.5 mol dm−3 NaOH(aq) are mixed. What are the concentrations of NaOH(aq) and NaCl(aq) in the resulting solution? [NaOH(aq)] / mol dm−3 [NaCl(aq)] / mol dm−3 A 0.25 0.50 B 0.25 1.0 C 0.50 0.50 D 0.50 1.0 4 Use of the Data Booklet is relevant to this question. Which ion contains the greatest number of unpaired electrons? A N− B F2+ C Cr2+ D Co2+

3 © Raffles Institution 2021 9729/J/21 [Turn Over 5 Which statement regarding neutrons and electrons is incorrect? A They are oppositely charged. B They are found in different parts of the atom. C The neutron has a greater mass than the electron. D The number of electrons in an atom may be different from the number of neutrons. 6 Use of the Data Booklet is relevant to this question. Which statement regarding the valence shell of an atom of boron is correct? A It contains three half-filled orbitals. B Its orbitals are all of the same shape. C Its electrons are all at the same energy level. D It can accommodate a maximum of eight electrons. 7 Which row correctly describes the bonding in the molecule below? number of σ bonds number of π bonds A 15 3 B 15 4 C 18 3 D 18 4

4 © Raffles Institution 2021 9729/J/21 [Turn Over 8 Which of the following statements is correct? A SiO2 has a higher boiling point than CO 2 as SiO 2 has stronger instantaneous dipole - induced dipole interactions. B Mg has a higher melting point than Na as Mg has more valence electrons. C AlCl3 has a lower melting point than AlF3 as AlCl3 has weaker ionic bonds. D has a higher boiling point than as the first compound has intramolecular hydrogen bonding. 9 The electronegativity values of carbon and hydrogen are similar. Both oxygen and chlorine are more electronegative than carbon. Which molecule has the largest overall dipole? A B C D 10 Which molecules contain at least one 90º bond angle? 1 PCl5 2 SF6 3 XeF4 A 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3

5 © Raffles Institution 2021 9729/J/21 [Turn Over 11 Use of the Data Booklet is relevant to this question. The density of a mixture of helium and xenon is 5.00 g dm–3 at 25 °C and 100 kPa. What is the mole fraction of helium in the mixture? A 0.050 B 0.059 C 0.941 D 0.950 12 Which of the following graphs are correct for 1 mol of an ideal gas? 1 2 3 constant T constant p constant T A 1 and 2 only B 1 and 3 only C 2 and 3 only D 2 only 13 Use of the Data Booklet is relevant to this question. Which of the following shows the correct arrangement o f ions in increasing magnitude of their hydration energies? A Cr2+ < Fe2+ < Ti3+ B Fe2+ < Cr2+ < Ti3+ C Ti3+ < Cr2+ < Fe2+ D Ti3+ < Fe2+ < Cr2+ 14 Which statement regarding the following reaction is incorrect? C2H4(g) + H2(g) → C2H6(g) Hr < 0 A More energy is released during bond forming than absorbed during bond breaking. B Hr can be calculated using Hcombustion(C2H4(g)) and Hcombustion(C2H6(g)) only. C S < 0 because the number of gaseous molecules decreases. D The reaction is spontaneous only at low temperatures. higher p lower p V T higher T lower T p 1/V lower T higher T pV p

6 © Raffles Institution 2021 9729/J/21 [Turn Over 15 An energy level diagram involving carbon and oxygen is shown below. Which equations are correct? 1 P = Hatomisation(C(s)) + Hatomisation(O2(g)) 2 S = Hformation(CO2(g)) – P 3 Q = Hcombustion(C(s)) – R 4 R = Hcombustion(CO(g)) A 1 and 3 only B 1 and 4 only C 2 and 3 only D 2, 3 and 4 only C(g) + 2O(g) energy / kJ mol–1 CO2(g) CO(g) + O(g) C(s) + O2(g) 0 P Q R S

7 © Raffles Institution 2021 9729/J/21 [Turn Over For examiner’s use Section B (30 marks) This section consists of 3 questions. Answer all the questions in this section in the spaces provided. 1 Use of the Data Booklet is relevant to this question. Thallium is a metal that can cause poisoning in animals , and thallium salts were used in rat poison in the past. A toxicologist can determine the amount of thallium in the bones of a rat poisoned to death by following the procedures stated below. Dissolving the bone: 1. A sample of the bone is weighed and dissolved in concentrated HNO3. 2. Concentrated H2SO4 is added to the resulting solution from s tep 1. A lot of white precipitate, most of whi