MJC H2 Chem 2013 Prelim P1 QP Soln

©chemistry@meridian jc Name ________________________ Class: ___________ Reg Number: _____ MERIDIAN JUNIOR COLLEGE JC 2 Preliminary Examination (ANSWERS ON THE LAST PAGE) Higher 2 _________________________________________________________________________ Chemistry 9647 Paper 1 Multiple Choice 26 September 2013 1 hour Additional Materials: OMR Sheet Data Booklet ___________________________________________________________________ INSTRUCTIONS TO CANDIDATES Write your name, class and register number in the spaces provided at the top of this page. There are forty questions in this section. Answer all questions. For each question, there are four possible answers labelled 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 use of OMR answer sheet. You are advised to fill in the OMR Answer Sheet as you go along; no additional time will be given for the transfer of answers once the examination has ended. This document consists of 24 printed pages and 1 blank page. Use of OMR Answer Sheet Ensure you have written your name, class register number an d class on the OMR Answer Sheet. Use a 2B pencil to shade your answers on the OMR sheet; erase any mistake 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 shade 01 in the index number column. If your register number is 21, then shade 21 in the index number column.   865

Section A For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 The polyoxometallate W 72Mn12Si7O268 40- was recently ident ified in a crystal garden. Which row gives oxidation states of tungsten and manganese that are consistent with this formula? oxidation state of tungsten oxidation state of manganese A +3 +2 B +3 +3 C +6 +2 D +6 +3 2 During the 1950s, a Sydney woman killed three family members and a friend by putting rat poison into the food and drinks she gave them. The crystalline toxic white compound, thallium sulfate, Tl2SO4, is water soluble. A single dose of more than 500 mg is fatal. At what minimum concentration of thallium sulfate does a 200 cm 3 cup of tea provide a fatal amount of the poison? A 0.990 x 10 -3 mol dm-3 B 1.66 x 10 -3 mol dm-3 C 4.96 x 10 -3 mol dm-3 D 8.32 x 10 -3 mol dm-3 3 Which compound is composed of a cation and anion(s) that do not contain the same number of electrons as each other? A LiH B NaOH C NH 4F D TiC l3 866

2 ©chemistry@meridian jc [Turn over 4 Which transition metal ion in the following species has only one unpaired electron in its d orbitals? A [CoC l4]2- B [Fe(H 2O)5(F)]2+ C [Mn(CN) 6]3- D [VO(H 2O)5]2+ 5 In which of the following pairs of com pounds is the first member more volatile than the second? A CH 3CH2CH2CH3 and CH3CH(CH3)CH3 B CH3CH2OH and CH3OCH3 C CH3CH2COOH and CH3CH(NH2)COOH D 6 A vessel containing ammonia gas is heated to a constant temperature such that the equilibrium below is established. 2NH 3(g) N2(g) + 3H2(g) The value of the pressure p is then found to be 35 % greater than if only NH3(g) were present. What is the mole fraction, x, of nitrogen present in this equilibrium mixture? A 0.130 B 0.175 C 0.389 D 0.611 C C CH3 HH H3C C C CH3 H H H3C and 867

3 ©chemistry@meridian jc [Turn over ∆H progress of reaction ∆H progress of reaction ∆H progress of reaction ∆H progress of reaction 7 The base catalysed hydrolysis of a meth yl ester has the following reaction path.   R C O OCH3 R C O OCH3 R C O OH OH OH OCH3 RCO2 - +C H 3OH+ step 1 step 2 step 3 slow   What will be the reaction pathw ay diagram for the first two steps of this hydrolysis? A B C D 868

4 ©chemistry@meridian jc [Turn over 8 A dilute solution of hydrogen peroxide decomposes slowly in aqueous solution according to the following equation: 2H2O2(aq) → 2H2O(l) + O2(g) A solution with an original concentration of 3.00 mol dm -3 was placed in a bottle contaminated with transition metal ions, which act as catalyst for the decomposition. The rate of decomposit ion was measured by withdrawing 10.0 cm 3 portion at various times and titrating with acidified 0.05 mol dm -3 KMnO4(aq). The following results were obtained. How long has the solution in the bottle been contaminated before the first portion was withdrawn for titrati on? Assume that 5 mol of H 2O2 reacts with 2 mol of KMnO4. A 14 minutes B 42 minutes C 84 minutes D 112 minutes 0 5 10 15 20 25 30 0 5 10 15 20 25 30 Volume of KMnO4(aq) / cm3 Time / min 869

©chemistr 9 ry@meridian jc The curv e molecules Which is a A Th e ene B Th e ene C Th e ene D Th e ene e Y and t h s and the a a possible o e distributio ergy by val e distributio ergy by val e distributio ergy by val e distributio ergy by val he value E ctivation e outcome if on of ener ue V. on of ener ue V. on of ener ue W. on of ener ue W. 5 Ea repres e energy for a f the reacti rgies will b rgies will b rgies will b rgies will b nt the dis t an uncataly on is catal e given by e given by e given by e given by tribution o ysed gase ysed? y curve X a y curve Y a y curve Y a y curve Z a [Tu of energie s ous reactio and the ac and the ac and the ac and the ac urn over s of the on. ctivation ctivation ctivation ctivation 870

6 ©chemistry@meridian jc [Turn over 10 Citric acid is a weak monobasic acid. Which of the following pair of solutions, when mixed in equal volumes, will give t he best buffer solution that resists pH changes when a small amount of acid or base is added? A 0.5 mol dm -3 of citric acid and 0.5 mol dm-3 of sodium hydroxide B 0.5 mol dm -3 of citric acid and 0.125 mol dm-3 of barium hydroxide C 1.0 mol dm -3 of sodium citrate and 0.25 mol dm-3 of sulfuric acid D 1.0 mol dm -3 of sodium citrate and 0.5 mol dm-3 of citric acid 11 Sucrose, commonly called table sugar is highly soluble, as shown in the graph, and it dissolves according to C12H22O11(s) C 12H22O11(aq) H = +4.75 kJ mol1 A cup of coffee was made with 200 ml of water at 80 oC and as much sugar as would dissolve. It was left to cool to 60oC. During cooling from 80oC to 60oC A the fraction of [C 12H22O11(aq)]/[C12H22O11(s)] remains unchanged. B the system responds to the change in temperature by absorbing more heat. C the rate of forward reaction increas es as the system can release heat more easily. D the position of equilibrium moves left as the rate of the reverse reaction is greater than that of the forward reaction. 0 100 200 300 400 500 600 40 50 60 70 80 90 100 Solubility (g/ 100g H2O) Temperature oC Sucrose Solubility 871

©chemistr 12 A ry@meridian jc Artificial k suffering membrane dialysis flu The figure What are hemodialy b l A B C D kidney di a from kid n e is used uid. below sho the corr e ysis proces lood d   + + alysis, suc ney failu r to allow w ows a typic ect signs o ss? dialysis flu +   + 7 ch as he m re. Durin g waste ma t cal hemodi of S for uid modialysis g hemodi terials to p ialysis set blood a n is used alysis, a pass from up. nd dialysis [Tu to treat p semi-per the bloo d s fluid du r urn over patients rmeable d to the ring the 872

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