2017 HCI H1 Chemistry Prelims P1 Questions

This document consists of 11 printed pages (including this cover page) HWA CHONG INSTITUTION Preliminary Examinations Higher 1 NAME CT GROUP 16S CHEMISTRY Paper 1 Multiple Choice 8872/01 20 September 2017 Additional Materials: Data Booklet Optical Mark Sheet (OMS) 50 minutes INSTRUCTIONS TO CANDIDATES: Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Write your name, Centre number and index number on the Answer Sheet in the spaces provided. Complete the information on the optical mark sheet (OMS) as shown below. 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 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 2017 HCI Preliminary Examination H1 Chemistry Paper 1 Section A 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. Which one of the following has the same number of particles as one mole of magnesium atoms? A the number of ions in 2 dm 3 of 0.25 mol dm─3 of aqueous hydrochloric acid B the number of delocalised electrons in one mol of copper metal C the number of atoms in 71 g of chlorine gas D the number of ions in 58.5 g of sodium chloride 2 What mass of carbon dioxide will be formed by the complete combustion of 4.00 g of butan-1-ol? A 2.38 g B 3.03 g C 9.51 g D 12.1 g 3 The percentage by mass of water in a hydrated manganese(II) chloride salt is 36.4%. What is the empirical formula of the hydrated salt? A MnCl 2.2H2O C MnCl2.4H2O B MnCl2.3H2O D MnCl2.5H2O 4 Which of the following has the same electronic configuration as the chloride ion, Cl─? A Ca2+ B Na+ C Ne D F¯ 5 In which of the following reactions is the underlined element being reduced? A NH3 + HCl  NH4Cl B H2O2 + 2I¯ + 2H+  2H2O + I2 C 2V3+ + H2O2  2VO2+ + 2H+ D CaCO3  CaO + CO2

3 2017 HCI Preliminary Examination H1 Chemistry Paper 1 6 When heated, solid iodine forms iodine vapour. What does this information suggest about the nature of the particles in these two physical states of iodine? solid vapour A ionic atomic B ionic molecular C molecular atomic D molecular molecular 7 Hydrazine, N2H4, is useful as a rocket fuel. It has some properties that are similar to those of ammonia, NH3. hydrazine Why are hydrazine molecules more soluble in water than ammonia molecules? A There are more van der Waals' forces between hydrazine and water than between ammonia and water. B There are more hydrogen bonds between hydrazine and water than between ammonia and water. C There are stronger permanent dipole interactions between hydrazine and water than between ammonia and water. D The covalent bonding in hydrazine is stronger than that in water. 8 Which of the equations correctly define the standard enthalpy change of formation of a compound? A 2C(s) + 3H 2(g) + ½O2(g)  C2H5OH(l) B 2H2(g) + O2(g)  2H2O(l) C Na(s) + Cl(g)  NaCl(s) D C(g) + 2O(g)  CO2(g)

4 2017 HCI Preliminary Examination H1 Chemistry Paper 1 9 The graph below shows the fraction of ammonia in the equilibrium mixture obtainable if equilibrium was established under different temperature and pressure conditions during the Haber process. N 2(g) + 3H2(g) 2NH3(g) H < 0 What do H, J and K represent and what is the relative magnitude of J and K? H J and K relative magnitude A pressure temperature J > K B pressure temperature K > J C temperature pressure J > K D temperature pressure K > J 10 The table shows some data on two acid-base indicators. indicator approximate pH range of colour change colour change acid alkali thymolphthalein 9 – 10 colourless blue chlorophenol red 6 – 7 yellow red Which conclusion can be drawn about a solution in which thymolphthalein is colourless and chlorophenol red is red? A It is weakly acidic. B It is weakly alkaline. C It is neutral. D It is strongly alkaline. Fraction of NH3 in equilibrium mixture / % H J K 0

5 2017 HCI Preliminary Examination H1 Chemistry Paper 1 11 10 cm3 of 0.01 mol dm¯3 solution of H2SO4 is diluted with 90 cm3 of water. What is the pH of the resulting solution? A 1.7 B 2.0 C 2.7 D 3.0 12 An enzyme required in laboratory process operates at maximum efficiency when placed in an aqueous solution buffered at pH 5.6. Which combination of substances when dissolved in water would give the appropriate buffer solution? A 0.5 mol of HCl and 1 mol of CH 3COONa B 0.5 mol of HCl and 1 mol of CH3COOH C 1 mol of CH3COOH and 1 mol of NaOH D 1 mol of CH3COONH4 13 Which statement about the order of reaction is correct? A It is the sum of the powers of the concentrations of the species included in the rate equation. B It is the sum of the powers of the concentrations of the reactants and products. C It is the sum of the number of species included in the rate equation. D It is the sum of the number of moles on the left-hand side of the balanced chemical equation. 14 The diagram represents the Boltzmann distribution of molecular energies at a given temperature. Which of the following statements is incorrect? A The total number of molecules is constant at all temperatures. B When temperature decreases, the maximum of the curve is displaced to the left. C When temperature increases, the fraction of molecules with any given energy also increases. D When temperature increases, the fraction of molecules with energies greater than the activation energy increases. Fraction of molecules Energy

6 2017 HCI Preliminary Examination H1 Chemistry Paper 1 15 The reaction pathway diagram for a two–step reaction is shown below. Step 1: E          F Step 2: F  G Which statement about the reaction is correct?   A Step 2 is more exothermic than step 1. B The enthalpy change of reaction for both the forward and backward reaction of step 1 is the same. C The activation energy for the backward reaction of step 1 is 66 kJ mol–1. D The enthalpy change of reaction for the conversion of E to G is the sum of the enthalpy changes of step 1 and step 2. 16 The ions P3¯, S2¯ and Cl¯ have radii 0.212nm, 0.184nm and 0.181 nm respectively. Which one of the following correctly explains the decrease in radius from P 3¯ to Cl¯? A increase in both the total number of electrons and nuclear charge B total number of electrons remaining constant with an increase in nuclear charge C increase in the total number of electrons with nuclear charge remaining constant D decrease in the total number of electrons with nuclear charge remaining constant 17 Which of the following statements about the electrical conductivity of elements across Period 3 is incorrect? A Electrical conductivity increases from sodium to aluminium as the number of delocalised cations and electrons increases. B Sodium, magnesium and aluminium are good electrical conductors as their metallic lattices contain delocalised electrons. C Silicon is a semiconductor as the electrons within the covalent bonds are held tightly and are not easily delocalised. D Phosphorous, sulfur, chlorine and argon are non–conductors as there are no mobile charge carriers in their simple molecular structures. Progress of reaction Energy / kJ mol–1 55 121 168 E F G

7 2017 HCI Preliminary Examination H1 Chemistry Paper 1 18 Phosphorus can form PCl3 and PCl5. However, nitrogen can only form NCl3.