RI H2 CHEM P1 Prelim

-1- RAFFLES INSTITUTION 2011 YEAR 6 PRELIMINARY EXAMINATION HIGHER 2 CHEMISTRY 9647/01 Paper 1 Multiple Choice 26 September 2011 1 hour Additional Materials: Multiple Choice Answer Sheet Data Booklet READ THESE INSTRUCTIONS FIRST Do not open this question booklet until you are told to do so. Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, class and index number in the spaces provided on the Answer Sheet. 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 to be correct and record your choice with a 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 17 printed pages.

-2- Section A For each question there are four possible answers, A, B , C , and D. Choose the one you consider to be correct. 1 2.8 g of a metal, M, combines with 0.8 g of oxygen to form the oxide MO. The metal, M, also forms a second oxide in which the metal and oxygen are present in the ratio 7:3 by mass. What is the formula of the second oxide? A MO 2 B M2O C M2O3 D M3O2 2 Use of the Data Booklet is relevant to this question. When x mol of vanadium is added to a solution containing y mol of vanadium( III ) ions, vanadium( II ) ions are formed in the resultant solution. Which of the following are possible values of x and y if vanadium reacts completely and the resultant solution contains equal number of moles of vanadium( III ) ions and vanadium( II ) ions? x y A 1 2 B 1 3 C 1 5 D 2 3 3 Bromine trifluoride is a liquid at room temperature . It shows an electrical conductivity high enough to indicate that some auto-ionisation o ccurs, which is usually represented by the following equation: 2BrF 3 ⇋ BrF 2 + + BrF 4 – Which of the following is correct regarding BrF 3, BrF 2 + and BrF 4 – ? A BrF 3 is planar while BrF 4 – is non-planar. B BrF 2 + is linear while BrF 4 – is tetrahedral in shape. C The F–Br–F bond angle in BrF 3 is smaller than that in BrF 4 – . D There are more lone pairs of electrons around the Br atom in BrF 3 than that in BrF 2 +. 4 Which of the following cannot be explained by hydrogen bonding? A the existence of the hydrogen-difluoride anion, HF 2 – B the difference in volatility between pentan-1-ol a nd hexan-1-ol C the difference in melting point between 2-nitrophe nol and 4-nitrophenol D the higher than expected relative molecular mass o f ethanoic acid in benzene

-3- 5 Buckminsterfullerene has the formula, C 60 . Its structure is shown below. The bonding in buckminsterfullerene is similar to that in graphite. Which of the following is correct? A All the bond angles in buckminsterfullerene are 12 0 o. B There are delocalised electrons in buckminsterfull erene. C The melting point of buckminsterfullerene is highe r than that of graphite. D On complete combustion, buckminsterfullerene forms carbon dioxide and water. 6 Deuterium, 2H, is an isotope of hydrogen. In an experiment, 3.7 g of a gas X at 25 oC was found to occupy the same volume as 0.368 g of deuterium gas at 17 oC. Both gases were at the same pressure. What is the relative molecular mass of the gas X? A 17 x368 . 0 25 x7 . 3x0 . 2 B 290 x368 . 0x0 . 2 298 x7 . 3 C 298 x368 . 0 290 x7 . 3x0 . 4 D 290 x368 . 0 298 x7 . 3x0 . 4 7 The diagram shows the Maxwell-Boltzmann energy dis tribution curves for molecules of a sample of a gas at two different temperatures. Which letter on the axes represents the most proba ble energy of the molecules at the lower temperature? [Turn over A B C D

-4- 8 Use of the Data Booklet is relevant to this question. In an experiment to determine the enthalpy change of solution of ammonium nitrate in water, 8.00 g of solid ammonium nitrate ( Mr = 80.0) was added to 50 g of water and the temperature of the resultant solution monitored at various time intervals. Using data from the above experiment, the followin g graph was obtained. time of mixing of reactants What is the enthalpy change of solution of ammoniu m nitrate based on the data from the above experiment? A +19.4 kJ mol –1 B +20.1 kJ mol –1 C +20.9 kJ mol –1 D +22.6 kJ mol –1

-5- 9 In 1944, T. Ellingham published plots of ∆ Go against temperature T for a number of reactions. Today, such plots are called Ellingham diagrams. An Ellingham diagram for three reactions involving the oxidation of C and CO is shown below. Which of the following shows correctly the three r eactions corresponding to I, II and III in the above Ellingham diagram? I II III A 2CO + O 2 → 2CO 2 C + O 2 → CO 2 2C + O 2 → 2CO B 2C + O 2 → 2CO 2CO + O 2 → 2CO 2 C + O 2 → CO 2 C C + O 2 → CO 2 2CO + O 2 → 2CO 2 2C + O 2 → 2CO D 2CO + O 2 → 2CO 2 2C + O 2 → 2CO C + O 2 → CO 2 10 A chemical plant illegally dumped some radioactive waste in a landfill. This waste composed of two radioactive isotopes M and N. The half-life of M is 3 days whereas that of N is 2 days. The authorities found out about this il legal dumping only when the waste had been in the landfill for 12 days. They did an immediate analysis on a sample of the waste and found equal amounts of M and N. Considering that the decay of radioactive isotopes follows first-order kinetics, what is the molar ratio of M to N if the waste had been in the landfill for 6 days? M : N A 1 : 4 B 1 : 2 C 2 : 1 D 4 : 1 [Turn over

-6- 11 The kinetics of the reaction below was studied usi ng the method of initial rates. I– (aq) + C lO– (aq) → IO– (aq) + C l– (aq) Experiment Initial [ I– ] / mol dm –3 Initial [C lO– ] / mol dm –3 Initial [OH – ] / mol dm –3 Initial rate / mol dm –3 s–1 1 0.001 3 0.012 0.100 9.4 x 10 –3 2 0.0026 0.012 0.100 18.7 x 10 –3 3 0.0013 0.018 0.100 14.0 x 10 –3 4 0.0026 0.018 0.050 56.1 x 10 –3 What is the overall order of the reaction? A 1 B 2 C 3 D 4 12 At a temperature T K, 0.80 mol of SO 2 and 0.40 mol of O 2 were introduced into a 10 dm 3 vessel and allowed to come to equilibrium. 2SO 2(g) + O 2(g) ⇋ 2SO 3(g) ∆ H < 0 The graph below shows the variations in the amount s of SO 2 and SO 3 in the system with time. A change was made to the system at time t. What was the change made at time t? A a catalyst was added B the temperature was decreased C an inert gas was added at constant volume D 0.05 mol of O 2 was added at constant volume 13 The pH of pure water is 6.88 at 32 oC. The pH of a saturated solution of a Group II hydroxide is 11.70 at the same temperature. What is the numerical value of the solubility prod uct of this hydroxide at 32 oC? A 6.3 x 10 – 8 B 3.3 x 10 – 7 C 1.3 x 10 – 5 D 3.8 x 10 – 5 OH –

-7- 14 In an experiment, a cell was set up to obtain pure