2020 YIJC Prelim Exam Paper 1 QP

©YIJC [Turn over YISHUN INNOVA JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME CG INDEX NO CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 17 September 2020 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name and class 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 booklet. The use of an approved scientific calculator is expected, where appropriate. This document consists of 12 printed pages.

2 ©YIJC [Turn over 1 Which statement about the electrons in a ground state carbon atom is correct? A The occupied orbital of highest energy is spherical. B The occupied orbital of lowest energy is spherical. C There are more electrons in p orbitals than there are in s orbitals. D Electrons are present in four different energy levels. 2 Use of the Data Booklet is relevant to this question. In an experiment, an ore sample containing phosphorus and an unknown element X is vapourised, ionised and passed through an electric field at the same speed. What could be the identity of element X? A sulfur B silicon C sodium D nitrogen 3 Which molecule or ion contains the smallest bond angle? A C2H4 B HCHO C NH4+ D NH3 4 Which compounds contain an odd number of  bonds? 1 C2H2 2 C2H5OH 3 CH3CHO 4 CH3CO2H A 1, 2, 3 and 4 B 1 and 2 only C 1 and 4 only D 2 and 3 only beam of P+ and X+ +  P+ X+

3 ©YIJC [Turn over 5 Three identical flasks each contains the same mass of gases X, Y and Z respectively. The temperature, t, and pressure, p, of each flask are indicated below. gas temperature pressure X t p Y t 2p Z 2t p Assuming ideal gas be haviour, what is the order of the relative molecular masses , Mr, of the three gases? A Mr(Z) > Mr(X) > Mr(Y) B Mr(Z) > Mr(Y) > Mr(X) C Mr(X) > Mr(Y) > Mr(Z) D Mr(X) > Mr(Z) > Mr(Y) 6 Use of the Data Booklet is relevant to this question. How many atoms are there in 500 cm3 of carbon dioxide at r.t.p.? A 1.25 1022 B 1.34 1022 C 3.76 1022 D 9.0 1026 7 In oil refineries, an important process is the recovery of any sulfur from petroleum. Sulfur compounds are converted into the gas hydrogen sulfide, H 2S, by using a catalyst. The H 2S is then oxidised by using a controlled amount of air to give steam, H2O(g), and sulfur, S(s). The enthalpy change of formation of H2S(g) is –20.5 kJ mol–1 and that of H2O(g) is –243.0 kJ mol–1. What is the enthalpy change of reaction per mole of H2S? A –202.5 kJ mol–1 B –222.5 kJ mol–1 C –263.5 kJ mol–1 D –445.0 kJ mol–1

4 ©YIJC [Turn over 8 The equation describes the equilibrium between solid silver chromate and its aqueous ions. Ag2CrO4(s) ⇌ 2Ag+(aq) + CrO42(aq) Ho = +61 kJ mol1 So = 30 J K1 mol1 What can be deduced from the information about this equilibrium? 1 At 25 oC, Go is negative. 2 At 25 oC, silver chromate is almost insoluble in water. 3 At 95 oC, silver chromate is more soluble in water than at 25 oC. A 2 only B 1 and 3 only C 2 and 3 only D 1, 2 and 3 9 In an enzyme-catalysed reaction, the rate is affected by the concentration of substrate as shown in the graph below. The steps that are common to most enzyme-catalysed reactions are enzyme + substrate  enzyme–substrate complex (fast) enzyme–substrate complex  enzyme + product (slow) Which conclusion can be drawn about the kinetics of the enzyme-catalysed reaction? 1 When [substrate] is low, the reaction is first order with respect to the substrate. 2 When [substrate] is high, the reaction is zero order with respect to the substrate. 3 The rate equation is rate = k[enzyme–substrate]. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 3 only 0 0 initial rate [substrate]

5 ©YIJC [Turn over 10 A radioactive element has two isotopes, X and Y, with half-lives of 5min and 15min respectively. An experiment starts with 4 times as many atoms of X as of Y. Radioactive decay is a first order reaction. How long will it be before the number of atoms of X left equals the number of atoms of Y left? A 5 min B 10 min C 15 min D 20 min 11. Nitrogen dioxide, NO2, is a brown gas. Dinitrogen tetroxide, N2O4, is a colourless gas. An equilibrium is established between NO2 and N2O4 in a closed vessel. 2NO2(g) ⇌ N2O4(g) ΔH = 57 kJ mol1 brown colourless Which row describes the effects of changing conditions on the colour of an equilibrium mixture of NO2 and N2O4? increasing pressure increasing temperature A colour becomes darker colour becomes darker B colour becomes darker colour becomes lighter C colour becomes lighter colour becomes darker D colour becomes lighter colour becomes lighter 12 What is a satisfactory indicator for the titration of 0.1 mol dm 3 ethanoic acid with 0.1 mol dm 3 aqueous ammonia? A bromothymol blue (pH range 6.0 – 7.6) B methyl red (pH range 4.2 – 6.3) C phenolphthalein (pH range 8.2 – 10.0) D there is no suitable indicator 13 What is the pH of an aqueous solution containing 0.1 mol dm 3 sodium benzoate and 0.01 mol dm3 benzoic acid? [Ka (benzoic acid) = 6 105 mol dm3] A 3.22 B 4.22 C 4.78 D 5.22

6 ©YIJC [Turn over 14 A solution contains a mixture of 1 103 mol dm3 of bromide, fluoride, iodide and sulfate ions. Values of the various lead(II) compound solubility product, Ksp, are given in the table. Ksp lead(II) bromide 4.0 105 lead(II) fluoride 2.7 108 lead(II) iodide 7.1 109 lead(II) sulfate 1.6 108 Which lead(II) compounds will be precipitated first when 0.01 mol dm-3 of lead(II) nitrate is added dropwise into the solution? A lead(II) bromide B lead(II) fluoride C lead(II) iodide D lead(II) sulfate 15 Which statements about the Period 3 elements from sodium to chlorine are correct? 1 There is a change from metallic behaviour to non -metallic behaviour across the period. 2 Their compounds show an increase in the maximum oxidation number across the period. 3 The melting points of the elements decrease across the period. A 1, 2 and 3 B 1 and 2 only C 1 only D 2 and 3 only 16 The elements radon (Rn), francium (Fr) and radium (Ra) are consecutive in the Periodic Table. What is the order of their first ionisation energies? least endothermic most endothermic A Fr Ra Rn B Fr Rn Ra C Ra Fr Rn D Rn Ra Fr

7 ©YIJC [Turn over 17 The chloride of element J neither reacts with nor dissolves in water. Which element could be J? A aluminium B carbon C magnesium D silicon 18 Which graph correctly describes a trend found in Group 17? A B C D 19 How many constitutional isomers are there in a molecule with  molecular formula C7H12O2 and  a five-membered ring and  a ketone group and  a tertiary alcohol group? A 4 B 6 C 7 D 9 20 Complete combustion of a sampl