NYJC H2 CHEM P1 Prelim

NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY 9647/01 Paper 1 Multiple Choice 27 September 2016 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 J2/16 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 In an experiment, lanthanum, 57La, was reacted with hydrogen to produce the non-stoichiometric ionic compound LaH 2.9. Assuming that the compound contains H, La2+ and La3+, what is the percentage of La3+ present in LaH2.9? A 10% B 20% C 80% D 90% 2 The two most common isotopes of titanium are Ti22 56 and Ti22 58 . Which statement about the isotopes of titanium is correct? A Both isotopes have more electrons than neutrons. B One of the isotopes has more protons than the other. C The electronic configuration of Ti2+ ion for both isotopes is the same. D In the same electric field strength, Ti22 56 will be deflected more than Ti22 58 . 3 Which compound does not have a co-ordinate bond? A CO B CS2 C NO3 D NH4+ 4 In which of the following pairs do the species have the same bond angle? A H2O2 and N2F2 B PH3 and SF3+ C POCl3 and SO32 D HCHO and BrF3

3 H2 Chemistry 9647/01 NYJC J2/16 PX [Turn over 5 Two glass vessels M and N are connected by a closed valve. M contains helium at 20 C at a pressure of 1 × 105 Pa. N has been evacuated, and has three times the volume of M. In an experiment, the valve is opened and the temperature of the whole apparatus is raised to 100 C. What is the final pressure in the system? A 3.18 × 104 Pa B 4.24 × 104 Pa C 1.25 × 105 Pa D 5.09 × 105 Pa 6 Which value would be required to estimate the lattice energy for the hypothetical ionic compound MgH? A the electronic affinity of hydrogen B the first ionisation energy of hydrogen C the magnesium–hydrogen bond energy D the standard enthalpy change of formation of MgH2 M N

4 H2 Chemistry 9647/01 NYJC J2/16 PX 7 A student performed an experiment to investigate a hypothetical reaction. 2A + B  C The graph of [A] against time(t) for the experiment is shown below. Given that the initial [B] is 2.0 mol dm 3 and unit s for the rate constant is mol1 dm3 min1, which of the following statements is true? A The reaction is elementary. B The half-life of the reaction remains constant when a catalyst is added. C The gradient of tangent at t = 0 min increase s by four times when the initial [B] doubles. D The half -life of the reaction remain s constant when [ A] doubles but ha lved when [B] doubles. 8 Glauber’s salt, Na2SO4 Å 10H2O, was used by J. R. Glauber in the 17th century as a medicinal agent. At 25 oC, the numerical value of the equilibrium constant, Kp for the loss of water of hydration from Glauber’s salt is 4.08 × 10−25. Na2SO4 Å 10H2O(s) Ý Na2SO4(s) + 10H2O(g) Which of the following statements can be correctly deduced about this equilibrium reaction? A The reaction reaches dynamic equilibrium when the forward and reverse rate constants are equal. B The numerical value of the vapour pressure of water at 25 oC in a closed container holding a sample of Na2SO4 Å 10H2O(s) is 3.64 × 10−3. C The ratio of the hydrated form to anhydrous form of the Glauber’s salt remains the same when nitrogen gas is added while keeping the total pressure of the system constant. D The numerical value of Kp will increase when temperature is increased. 0 20 40 0.0500 [A] 0.0125 0.0250 t / min

5 H2 Chemistry 9647/01 NYJC J2/16 PX [Turn over 9 Highly toxic disulfur decafluoride decomposes by a free-radical process. S2F10(g) Ý SF4(g) + SF6(g) In a study of the decomposition, S2F10 was placed in a 2.0 dm 3 flask and heated to 100 oC. The equilibrium [S2F10] was found to be 0.5 mol dm −3. More S2F10 was then added and the new equilibrium [S2F10] was 2.5 mol dm−3. What is the amount of S 2F10 reacted in terms of the equilibrium constant, Kc of the decomposition reaction when more S2F10 was added? A (0.5Kc)0.5 − (2.5Kc)0.5 B (2.5Kc)0.5 − (0.5Kc)0.5 C (2Kc)0.5 − (10Kc)0.5 D (10Kc)0.5 − (2Kc)0.5 10 Phosphorus acid, H3PO3, has two acid dissociation values: Ka1 = 1.0 × 102 mol dm3 Ka2 = 2.5 × 107 mol dm3 Which of the following statements is correct about H3PO3? I: H3PO3 is a dibasic acid as one of the H atom is bonded to P atom. II: The Kb values of H 2PO3 and HPO 32are 4.0 × 1012 and 1.0 × 1012 respectively. III: Ka2 is smaller than Ka1 because it gets increasingly difficult to remove a H + from a negatively charged ion. A I only B I & III C II & III D All statements are correct

6 H2 Chemistry 9647/01 NYJC J2/16 PX 11 The diagram below shows the change of pH produced when 20.0 cm 3 of trimethylamine was titrated with 0.01 mol dm3 of HCl(aq) at 25 oC. Which of the following statements is incorrect? A The Kb value of trimethylamine is 8.00 × 105. B When 35.00 cm3 of acid is added, pH of the solution is 2.7. C Phenolphthalein is not a suitable indicator for the above titration. D When concentration of HCl is doubled, the end point volume of the titration would be halved while the pH at equivalence point would remain the same. 12 The e.m.f of three different experiments was measured under standard conditions and the results are shown below: Experiment 1: W(s) + X2+(aq)  W2+(aq) + X(s) Eʅ cell > 0 Experiment 2: X(s) + 2Y+(aq)  X2+(aq) + 2Y(s) Eʅ cell < 0 Experiment 3: Z(s) + W2+(aq)  Z2+(aq) + W(s) Eʅ cell > 0 Which of the following statements is correct? A Z2+ is the strongest oxidising agent. B If concentration of Y +(aq) is lowered in experiment 2, the Eʅ cell would be more positive. C The reaction of Z(s) + W2+(aq)  Z2+(aq) + W(s) is spontaneous. D The reducing power decreases in the order Z>W>Y>X. 13 In a lead -acid battery reaction, the charging process is achieved by passing an electric current through the cell. The overall reaction equation for the charging process is given below. 2PbSO4 + 2H2O  Pb + PbO2 + 2H2SO4 25.00 Volume of acid / cm3 pH – 11 2

7 H2 Chemistry 9647/01 NYJC J2/16 PX [Turn over After charging, PbSO 4 on one plate is converted to PbO 2. The other plate is converted to Pb. When the two plates are connected, a current will flow, enabling the discharging process to take place. Which species is oxidised when the battery is discharged? A Pb B H2O C PbO2 D SO42 14 The diagram represents an unsuccessful attempt to prepare and collect sulfur dioxide. Which modification would make the experiment successful? A omitting flask X entirely B omitting flask Y entirely C using dilute sulfuric acid instead of dilute hydrochloric acid D collecting by upward delivery dilute hydrochloric acid heat sodium sulfite, Na2SO3 aqueous NaOH concentrated sulfuric acid X Y

8 H2 Chemistry 9647/01 NYJC J2/16 PX 15 Which of the following statements for strontium or its com