DHS H1 CHEM P1 QP with answer key

This document consists of 13 printed pages and 1 blank page. © DHS 2018 8873/01 [Turn Over Name: Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination 2018 Year 6 H1 CHEMISTRY 8873/01 Paper 1 Multiple Choice 24 September 2018 1 hour Additional Materials: Data Booklet Optical Mark Sheet INSTRUCTIONS TO CANDIDATES 1 Write your name, index number and class on this question paper and the OTAS Mark Sheet. 2 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 Optical Mark Sheet. 3 Each correct answer will score one mark. A mark will not be deducted for wrong answer. 4 Any rough working should be done in this booklet. 5 The use of an approved scientific calculator is expected, where appropriate. 6 On the OTAS Mark Sheet, please shade the code as “Class/Index number”. For illustration only: A student from class 6C38, with index number 02, should shade “3802”. 3 8 0 2

2 © DHS 2018 8873/01 1 Which option contains one mole of the stated particles? Note that D = H1 2 . A carbonate ions in 60 g of sodium carbonate B neutrons in 1.8 g of heavy water, D2O C electrons in 0.1 mol of OH– D oxygen atoms in 11.2 dm3 of O3, under s.t.p 2 NF3 can be obtained from the reaction between ammonia and fluorine gas. 4NH3 + 3F2 → NF3 + 3NH4F Which statement about the reaction is correct? A NH 3 undergoes disproportionation. B The oxidation number of nitrogen in NF3 is +3. C NH3 is a stronger oxidising agent than F2. D One mole of F2 loses two moles of electrons. 3 Use of the Data Booklet is relevant to this question. Which statement regarding 26Mg2+ and 27Al3+ ions is true? 1 26Mg2+ has more protons than 27Al3+. 2 Both ions have more neutrons than protons in their nuclei. 3 Both ions have outer electronic configuration 2s 22p6. 4 Both ions have the same number of neutrons. A 1 and 2 only B 1 and 3 only C 3 and 4 only D 2, 3 and 4 only 4 In which substance must covalent bonds break on melting? A calcium B silicon C sodium carbonate D ice

3 © DHS 2018 8873/01 [Turn Over 5 Valence Shell Electron Pair Repulsion theory can be used to predict the shapes of molecules and ions. Which of the following are the shapes of NO 2 and NO3– respectively? NO2 NO3– A linear trigonal planar B linear trigonal pyramidal C bent trigonal planar D bent trigonal pyramidal 6 Use of the Data Booklet is relevant to this question. Which graph shows the correct trend when the melting points of the oxides of elements Mg, Al, Si and P is plotted against its ionic radius? A Melting point of oxide Ionic radius of element . Al Mg. . . Si P B Melting point of oxide Ionic radius of element .Al Mg. . . Si P C Ionic radius of element . Al Mg . . . Si P Melting point of oxide D Ionic radius of element . Al Mg. . . Si P Melting point of oxide

4 © DHS 2018 8873/01 7 Two different Group 1 metals, K and L, were separately thrown into two beakers of cold water. K skipped on the water surface and effervesence was seen. K disappeared after sometime. L exploded upon contact with water. Which statement is false? A L could be rubidium if K is sodium. B K is a stronger reducing agent than L. C Hydrogen gas is given off when L came into contact with water. D The water in the beaker becomes basic upon reacting with K. 8 X2, Y2 and Z2 are Cl2, Br2 and I2 but are not necessarily in the given order. The table below recorded observations when these halogens are separately added to aqueous solutions containing the halide ions followed by the addition of an organic solvent, CCl 4. Experiment Reactants Observation after shaking with CCl4 1 X2 (aq) + Y– (aq) Violet organic layer seen. 2 Y2 (aq) + X– (aq) (Observations not recorded) 3 Z2 (aq) + X– (aq) Orange-red organic layer seen. 4 Z2 (aq) + Y– (aq) Violet organic layer seen. Which statement could be deduced from the above experiments, given X2 (aq) is an orange solution? A The colour of the organic layer in Experiments 2 and 4 is the same. B Identity of Z2 is Br2. C In Experiment 3, there is no redox reaction occurring. D X2 is a stronger oxidising agent than Z2. 9 For which process is the enthalpy change always negative? A Melting of ice. B Reaction between an acid and a base. C Breaking a covalent bond of a diatomic molecule. D Forming a compound from its elements.

5 © DHS 2018 8873/01 [Turn Over 10 A rock sample was found to contain isotopes T and U which are radioactive. Initially, the ratio of the number of atoms of T to U in the rock sample is 1 : 16. The decay of isotopes T and U was found to follow first order kinetics. The half–life of T is 12 days while that of U is 3 days. How long, in days, will it take for a rock sample to contain a molar ratio of T to U of 4 : 1? A 6 B 12 C 18 D 24 11 The stoichiometry of a reaction is shown by the equation below. L(g) + M(g) ⇌ Q(g) + R(g) ∆H = –20 kJ mol –1 Two experiments were carried out in enclosed vessels which the rate of production of R was measured. The results are shown in the diagram below. 0 No of moles of R Time Experiment 1 Experiment 2 Which changes in the conditions might explain the results shown? 1 Temperature of the vessel in Experiment 2 is higher. 2 A smaller vessel is used in Experiment 2. 3 A catalyst is used in Experiment 2. A 1, 2 and 3 B 1 and 2 only C 2 and 3 only D 1 only 12 In which reaction is the first reactant not acting as a Bronsted-Lowry base? A NH3 + CH3Cl → CH3NH3+ + Cl– B OH– + HSO4– → H2O + SO42– C CH3OH + HClO4 → CH3OH2+ + ClO4– D HNO3 + H2SO4 → H2NO3+ + HSO4–

6 © DHS 2018 8873/01 13 Nanoparticle zinc oxide is an ingredient found in most sunscreens. The white bulk powder form of zinc oxide is not used even though it can absorb UV rays. Which statement about zinc oxide as a nanoparticle is true? 1 Zinc oxide is not white owing to the extremely small size of the nanoparticle. 2 Nanoparticle zinc oxide is water soluble. 3 Zinc oxide can absorb UV rays only when it is in nanoparticle form. 4 Since the surface area to volume ratio is very high, nanoparticle zinc oxide can be applied to the skin more evenly. A 1, 2 and 4 only B 2 and 3 only C 1 and 4 only D 3 and 4 only 14 Which statement explains why graphene is such a strong material? A Graphene is a crystalline allotrope of carbon. B Graphene exists as a three dimensional structure. C The layered structure of graphene allows the layers to slide over each other. D The strong network of carbon–carbon covalent bonds that exists in graphene. 15 A polymer is formed as a result of addition polymerisation and it has the following structure. CC F F F F n Which is the monomer? A CH F F H B CF F F F C CC H FF H D CC F FF F

7 © DHS 2018 8873/01 [Turn Over 16 Poly(vinyl alcohol) is a commonly used eye drop and has the structure shown below. CC H H H OH CC H H H OH CC H H H OH poly(vinyl alcohol) Which of the following properties makes poly(vinyl alcohol) suitable for its use? 1 The polymer is transparent. 2 It is fairly soluble in water. 3 It has high heat resistance. 4 It attracts water to itself. A 1, 2 and 4 only B 2 and 3 only C 1 and 4 only D 3 and 4 only 17 Chloralose is a drug that is commonly used in neuroscience as an anesthetic. OO O OH OH OH chloralose Cl Cl