NYJC H2 Chem 2012 Prelim P1 QP

NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY 9647/01 Paper 1 Multiple Choice 21 September 2012 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, class and tutor’s name on the Answer Sheet in the spaces provided unless this has been done for you. There are forty 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 you 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. This document consists of 20 printed pages and 0 blank page. [Turn over

2 H2 Chemistry 9647/01 NYJC J2/12 PX 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 mass percentage of magnesium in a mixture of magnesium chloride and magnesium nitrate was found to be 21.25%. What mass of magnesium chloride is present in 100 g of the mixture? A 47 g B 51 g C 53 g D 56 g 2 The use of the Data Booklet is relevant to this question. The successive ionisation energies, in kJ mol –1 , of an element X are given below. 870 1800 3000 3600 5800 7000 13200 What is X? A 8O B 33 As C 52 Te D 53 I 3 Iodine and phosphorus each form a trifluoride. Wh at are the shapes of these two molecules? IF 3 PF 3 A trigonal planar trigonal pyramidal B T-shaped trigonal pyramidal C trigonal pyramidal trigonal planar D T-shaped trigonal planar

3 H2 Chemistry 9647/01 NYJC J2/12 PX [Turn over 4 Which of the following diagrams correctly describe s the behavior of a fixed mass of an ideal gas? ( T is measured in K.) A B C D constant T p V 0 0 constant p V T 0 constant T p ρ 0 constant T pV p

4 H2 Chemistry 9647/01 NYJC J2/12 PX Questions 5 and 6 refer to the “OXO” reaction shown below. The “OXO” reaction shown below is industrially impo rtant for making alcohols, aldehydes and carboxylic acids. For example, butan al can be synthesised from propene, C 3H6, according to the following scheme. It can then b e converted to butan-1-ol and butanoic acid. CH 3CH=CH 2(g) + CO(g) + H2(g) Ý CH 3CH 2CH 2CHO(g) propene butanal 5 The value of ∆ G for this reaction is negative. What is the sign of ∆ S and ∆ H for the above reaction? ∆ S ∆ H A + + B + − C − + D − − 6 Use of the Data Booklet is relevant to this question. Taking the bond energy for the C /rdescendO bond in carbon monoxide to be 1077 kJ mol − 1 and using other appropriate bond energies, what is the numerical value of ∆ H for the above “OXO” reaction? A 137 kJ mol − 1 B 213 kJ mol − 1 C 573 kJ mol − 1 D 623 kJ mol − 1 7 The radioactive decay is a first order reaction. I f the rate of decay of a radioactive isotope decreases from 200 counts per minute to 25 counts per minute after 21.6 hours, what is its half-life? A 2.4 hours B 6.5 hours C 7.2 hours D 7.8 hours

5 H2 Chemistry 9647/01 NYJC J2/12 PX [Turn over 8 Which of the following statements correctly explai ns why a small increase in temperature leads to a significant increase in the rate of a gaseous reaction? A The average kinetic energy of the molecules is sli ghtly greater at a higher temperature. B The proportion of molecules with any given energy increases. C The frequency of collisions between molecules is g reater at a higher temperature. D The frequency of collisions between molecules with kinetic energy greater than the activation energy is greater at a higher temperature. 9 An equilibrium can be represented by the following equation: P(aq) + Q(aq) ⇋⇋⇋⇋ 2R(aq) + S(aq) In a certain mixture, the equilibrium concentration of Q is 10 mol dm − 3. What will be the new equilibrium concentration of Q if 5 mol of pure Q is dissolved in the mixture? A 15 mol dm − 3 B between 10 mol dm − 3 and 15 mol dm − 3 C 10 mol dm − 3 D between 5 mol dm − 3 and 10 mol dm − 3 10 Which of the following correctly lists 0.10 mol dm –3 solutions of HCl, KCl, NH 4Cl, KOH and KCN in order of increasing pH? A HCl, KCl, KCN, NH 4Cl, KOH B HCl, NH 4Cl, KCl, KCN, KOH C HCl, KCl, NH 4Cl, KCN, KOH D KCl, KCN, KOH, HCl, NH 4Cl 11 Thorium hydroxide, Th(OH) 4, is a sparingly soluble salt. Which of the followi ng shows the correct expression of its molar solubilit y s (mol dm –3 ) in terms of its solubility product K sp ? A s = (Ksp )1/5 B s = (Ksp /4) 1/2 C s = (Ksp )1/5 /256 D s = (Ksp /256) 1/5

6 H2 Chemistry 9647/01 NYJC J2/12 PX 12 Use of the Data Booklet is relevant to this question. Using inert electrodes, a current was passed throug h two beakers containing aqueous silver sulfate and aqueous copper(II) nitra te, connected in series under standard conditions. What is the ratio of the mass of silver to copper deposited after the current was passed for t minutes? A 0.59 B 0.85 C 1.70 D 3.40 13 Use of the Data Booklet is relevant to this question. The circuit shown in the diagram was set up. What are the products formed at the anode and catho de and what is the substance present in the sludge after some time? anode cathode sludge A Cu 2+ Cu Ag B Fe 2+ Cu 2+ Ag C Ag +, Fe 2+ Cu 2+ Zn D Cu 2+ , Fe 2+ Cu Ag A 1.00 mol dm -3 Cu( NO 3)2(aq) 0.50 mol dm -3 Ag 2SO 4(aq) At 25 oC, 1 atm A 1.00 mol dm-3 CuSO 4(aq) At 25 oC, 1 atm pure Cu impure Cu containing Ag and Fe impurities sludge battery

7 H2 Chemistry 9647/01 NYJC J2/12 PX [Turn over 14 On descending Group II from magnesium to barium, w hich of the following statements is true? A The enthalpy change of hydration of the M 2+ ion becomes more exothermic. B The first ionisation energy increases. C The nitrates is less easily decomposed by heat to give brownish fumes. D The solubility of the Group II oxides decreases. 15 What is observed when aluminium chloride is added to excess water? solubility in water pH of resulting solution A insoluble 7.0 B very slightly soluble 6.5 C dissolves 5.0 D dissolves 3.0 16 Which of the following compounds has the highest m elting point? A NaCl B MgCl 2 C AlCl 3 D SiCl 4 17 Both aqueous bromine and aqueous chlorine appear a s yellow solutions. Which of the following reagents can be used to distinguish the two solutions? A aqueous chlorine B aqueous sodium chloride C aqueous sodium thiosulfate D aqueous iron(II) sulfate, followed by aqueous sodi um hydroxide

8 H2 Chemistry 9647/01 NYJC J2/12 PX 18 In the laboratory, there are three bottles labeled A, B and C. Each bottle contains one of the following reagents: CaCl2(aq), FeCl2(aq) and AgNO 3(aq). The tests were carried out using these reagents and the results were summarised in the table below: Tests Observations Mixing reagents A and B, followed by addition of NH 3(aq) A white ppt soluble in NH 3(aq) Mixing reagents A and C, followed by addition of NH 3(aq) A grey precipitate insoluble in NH 3(aq) What are the identities of the reagents A, B and C? A B C A CaCl 2 AgNO 3 FeCl 2 B FeCl2 AgNO 3 CaCl 2 C AgNO 3 FeCl 2 CaCl 2 D AgNO 3 CaCl 2 FeCl 2 19 Letters written on paper using aqueous ammonium th iocyanate are invisible until turned blood-red by brushing the paper with aqueous iron(III) chloride. If the ammonium thiocyanate is