MJC H2 CHEM P1

Reg NumberClass No part of this paper should be repro duced for commercial use without the prior written permission of Meridian Junior College. Candidate Name _____________________________ ©chemistry dept@mjc 1 Meridian Junior College 2009 JC 2 Preliminary Examination H2 Chemistry 9746 24 September 2009 1 hr Paper 1 MULTIPLE CHOICE QUESTIONS Additional Materials Data Booklet INSTRUCTION TO CANDIDATES Write your name, class and r egister number in the spaces provided at the top of this page. There are fourty questions in this section. Answer all questions. For each question, there are four possible answers labeled A, B, C and D. Choose the one you consider correct and record your choice in soft pencil on the OMR answer sheet. Read very carefully the instructions on the OMR answer sheet. You are advised to fill in the OMR An swer Sheet as you go along; no additional time will be given for the transfer of answers once the examination has ended. Use of OMR Answer Sheet Ensure you have written your name, class r egister number and class on the OMR Answer Sheet. Use a 2B pencil to sha de your answers on the OMR sheet; erase any mistakes cleanly. Multiple shaded answers to a question will not be accepted. For shading of class register number on the OMR sheet, please follow the given examples: If your register number is 1, then sha de 01 in the index number column. If your register number is 21, then sh ade 21 in the index number column. This question paper consists of 21 printed pages

1 The reaction between silicon tetrabromide, SiBr4, with moist ethoxyethane produces four oxobromides with the formulae SiO2Br8, Si2OBr6, Si3O2Br8 and Si4O3Br10. When 0.192 g of one of the oxobromides was completely reacted with water, all it s bromine was converted into bromide ions and produced 0.392 g of a cream precipitat e when an excess of silver nitrate was added. Which of the following shows the correct identity of the oxobromide which reacted with water? A SiO 2Br8 B Si2OBr6 C Si3O2Br8 D Si4O3Br10 2 Nitrogen oxides are air pol lutants. In a reaction, 0.20 mol of an oxide, NxOy was reacted with 20 dm 3 of hydrogen gas at room temperature and pressure and passed over a heated catalyst to produce ammonia and water as the only products. At the end of the reaction, 0.80 dm 3 of hydrogen gas remained. The ammoni a produced required 0.200 mol of sulphuric acid for complete neutralisation. The reaction of the oxide with hydrogen can be r epresented by the following equation: N xOy (g) + 2 2y 3x H2 (g)  x NH3 (g) + y H2O (l) What is the molecular formula of the oxide? A NO B NO2 C N2O D N2O4 3 In an experiment, H 2S was reacted with 24.00 cm 3 of 0.15 mol dm -3 of an unknown bromate ion, BrO x - in acidic medium to form sulphur of mass 0.289 g as well as bromine solution, Br2. What is the value of x in BrOx -? A 2 B 3 C 4 D 5 ©chemistry dept@mjc 2

1 4 Which of the following ions has mo re electrons than protons and more protons than neutrons? [ H = 1 1 H; D = H; T = 2 1 3H; C = 12 C; O =16 O ] 6 8 A CO 3 2- B H 2DO+ C OH - D TCO 3 - 5 Which transition metal ion in the following species has only one unpaired electron in its d orbitals? A [CoC l4]2- B [Fe(H2O)5(SCN)]2+ C [Mn(CN) 6]3- D [VO(H 2O)5]2+ 6 Which of the following is the most accurate representation of a graph of P/ vs T for an ideal gas? (P = pressure;  = density; T = temperature in oC) A B P/ T P/ T C D P/ P/ T T ©chemistry dept@mjc 3

7 Which of the following statements describes a phenomenon which cannot be explained by the relative size of the atoms involved? A Sulphur can form SF 6 but oxygen cannot form OF6. B The bond angle in H2S is smaller than the bond angle in H2O. C The boiling point of the group IV hydrides increases from C to Ge. D Though nitrogen and phosphorus are both in Group V, nitrogen can exist as NN molecules but phosphorus does not. 8 A small amount of solid lead iodide was added to a beaker of water, which was stirred. Most of the solid settled on the bottom of the beaker, but a little dissolved, establishing the equilibrium shown below: PbI2(s) Pb2+(aq) + 2I-(aq) The rates of the forward and reverse r eactions were monitored over time, producing the graph shown below: reaction rate reverse reaction forward reaction time t What happened at time t? A The beaker was cooled in an ice-bath. B A small amount of solid Pb(NO3)2 was added to the beaker. C A small amount of solid PbI2 was removed from the beaker. D A small amount of water was added to the beaker. ©chemistry dept@mjc 4

©chemistry dept@mjc 5 9 Values of ionic product for water at different temperatures are given below: Temperature / ºC 0 25 100 Kw / mol2 dm-6 1.1 x 10-15 1.0 x 10-14 5.1 x 10-13 What are the approximate values of the pH of pure water at 0ºC, 25ºC and 100ºC? pH of pure water at different temperature 0 ºC 25 ºC 100 ºC A 6.1 7.0 7.5 B 7.0 7.0 7.0 C 7.5 7.0 6.1 D 15.0 14.0 12.3 10 Which of the following statements about acids, bases and salts is correct? A 10 cm 3 of 0.02 mol dm -3 of ethanoic acid neutralised by 5 cm 3 of 0.02 mol dm-3 of sodium hydroxide produces a basic buffer. B 10 cm3 of 0.02 mol dm-3 of hydrochloric acid neutralised by 5 cm3 of 0.02 mol dm-3 of ammonia produces an acidic buffer. C 0.02 mol dm -3 of sodium ethanoate has a higher pH than 0.02 mol dm-3 of ammonium chloride. D 0.02 mol dm-3 of ethanoic acid has a higher pH than 0.02 mol dm -3 of sodium ethanoate. 11 Instant ‘heat packs’ are composed of a supersaturated solution of sodium acetate and a small flat disc of iron metal embedded in the liquid. Pressing the disc releases v ery tiny crystals of sodium acetate into the solution which then act as nucleation sites for the recrystallisatio n of the remainder of the salt solution. Which of the following reflects the correct signs of ∆H, ∆S and ∆G for the overall process of the reaction? ∆H ∆S ∆G A + - + B + + - C - + - D - - -

12 Use of the Data Booklet is relevant to this question. A blue solution containing only v anadium ions was mixed with 10 cm 3 of dilute sulphuric acid and titrated against 0.0200 mol dm-3 KMnO4. The Ecell was measured against a standard hydrogen electrode and the following graph obtained. Which of t he following lists the appr oximate electrode pot ential values, in volts, for the points X and Y? Point X Point Y A 0.34 1.52 B 1.00 1.52 C 0.34 1.67 D 1.00 1.67 13 Ron wanted to surprise his desir ed sweetheart, Hermione, with a gold heart-shaped pendant of total surface area 7 cm2. In the Potions laboratory, Ron set up an electrolytic cell to conduct the electroplating process whereby one of the electrodes used was platinum and the electrolyte was concentrated 2.0 mol dm-3 gold(III) chloride, AuCl3 solution. In the process, 0.025 mol of gas was lib erated at the platinum electrode at room temperature and pressure. What is the thickness of the gold coat ing, given that the density of gold is 19.3 g cm-3? A 0.0243 B 0.0486 C 0.0729 D 0.1458 ©chemistry dept@mjc 6

14 The following aqueous solutions were connected in series as shown below: Which of the following gives the co rrect representation for reactions occurring at electrodes A, D and F? Electrode A Electrode D Electrode F A Cu (s)  Cu2+ (aq) + 2e Ag+ (aq) + e 