RI H2 CHEM P1 QP Prelim

-1- RAFFLES INSTITUTION 2015 YEAR 6 PRELIMINARY EXAMINATION HIGHER 2 CHEMISTRY 9647/01 Paper 1 Multiple Choice 28 September 2015 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 c onsider correct and record your 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 16 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 Manganese occurs naturally in many oxides. A sample of a manganese oxide ore consists of a mixture of manganosite (MnO) and braunite (Mn 2O3), and contains Mn and O in the molar ratio of 0.7:1. What is the molar ratio of Mn2+:Mn3+ in the ore? A 1:6 B 1:5 C 1:4 D 1:3 2 Use of the Data Booklet is relevant to this question. Uranium, U, is able to form water-soluble salts in which it exists in different oxidation states. In an experiment, 20.00 cm 3 of 0.100 mol dm –3 Un+ ions was found to react with 40.00 cm 3 of 0.0200 mol dm–3 MnO4 – ions in acidic medium. If UO2 2+ ions were produced in the reaction, what is the value of n in Un+? A 4 B 3 C 2 D 1 3 Use of the Data Booklet is relevant to this question. In which of the following pairs do the two species contain the same number of unpaired electrons? A C+, N B O, P+ C Cr+, Fe2+ D Mn3+, Co+ 4 The successive ionisation energies, in kJ mol–1, of an element Z in period 3 are given below. 770 1542 3208 4331 16091 19805 23780 29287 Which of the following statements about Z is correct? A Z is a good conductor of electricity. B The chloride of Z dissolves in water to form its oxide and white fumes. C The oxide of Z reacts with dilute potassium hydroxide. D Z has a simple molecular structure. 5 Which feature is present in the ions CO3 2–, SO3 2–, NO3 – and HCO2 –? A all bond angles are 120o B one dative covalent bond C three sigma bonds D eight lone pairs of electrons

-3- 6 The following diagram shows the contents of three vessels which are joined togethe r by a connecting tube which has been evacuated. After the valves on the vessels are opened, the final pressure is measured and is found to be 0.675 atm. If all the vessels and the connecting tube are maintain ed at 30 oC, what is the volume of the connecting tube? A 0.023 dm3 B 0.040 dm3 C 0.056 dm3 D 0.094 dm3 7 The Maxwell-Boltzmann distribution for a gas at constant temperature is shown below. If the temperature of the gas is reduced by 10 oC, the graph changes shape. What happens to the values of n for the molecular energies X, Y and Z? X Y Z A higher higher higher B higher lower lower C lower lower higher D lower lower lower [Turn over

-4- 8 Use of the Data Booklet is relevant to this question. In a calorimetric experiment, m g of propan-1-ol is burnt. y % of the energy released is absorbed by 200 g of water, which rises in temperature by 50.5 oC. Given that the enthalpy change of combustion of propan -1-ol is –2020 kJ mol –1, which of the following expressions gives the value of y? A 200 x 4.18 x 50.5 x 60.0 x 100 2020 x m B 200 x 4.18 x 50.5 x 60.0 x 100 2020 x 1000 x m C m x 2020 x 1000 200 x 4.18 x (50.5 + 273) x 60.0 x 100 D m x 4.18 x 50.5 x 100 200 x 2020 x 1000 x 60.0 9 When 36.0 g of water boils at 100 oC, 81.4 kJ of heat is absorbed. Assuming that Hvap and Svap of water do not change with temperature, what is Gvap (in kJ mol–1) of water at 50 oC? A –2.18 B 0 C +5.46 D +10.91 10 A student carried out an experiment to investigate the decomposition of aqueous H2O2 and it was determined to be a first -order reaction. 75% of the H2O2 in a solution of concentration 0.10 mol dm3 decomposes in 5.0 minutes. The student performed anot her similar experiment using 0. 050 mol dm3 aqueous H 2O2 solution and with a suitable catalyst added. With all other conditions kept the same, 50% of the H 2O2 in this solution decomposes in x minutes. Which of the following is most likely the value of x? A 2.0 B 2.5 C 4.5 D 5.0 11 If a quantity of 2H2 were added to an equilibrium mixture represented by the equation 1H2(g) + I2(g) ⇌ 2 1HI(g), how many different types of hydrogen-containing molecules would be present when equilibrium was re-established? A 3 B 4 C 5 D 6

-5- 12 X and Y were mixed in a 2 dm 3 vessel and the whole system was allowed to reach equilibrium at temperature T K, as represented by the following equation: X(g) + Y(g) ⇌ 2Z(g) The concentrations of all gases were measured at one -minute intervals and the operating conditions were altered at the 4th and the 7th minute. The effects are shown in the graph below. Which of the following can be inferred from the given information? A The equilibrium constant, Kc, is 4.0 at the 3rd minute. B 0.10 mol of Y was added at constant volume at the 4th minute. C The volume of the vessel was decreased at the 7th minute. D The forward reaction rate was faster than the reverse reaction rate at the 8th minute. 13 In an experiment, 20.0 cm3 of 0.1 0 mol dm –3 hydrochloric acid was added to 25.0 cm3 of 0.10 mol dm–3 aqueous ethylamine (pKb = 3.25). What is the pH of the resulting solution? A 9.80 B 10.15 C 10.75 D 11.10 [Turn over

-6- 14 The numerical values of the solubility products of three metal sulfides are tabulated below. Compound Numerical value of solubility product CuS 8.5 x 1045 Ag2S 1.6 x 1049 Bi2S3 1.1 x 1073 Which of the following shows the three metal sulfides arranged in order of increasing molar solubility in water? A Bi2S3 < Ag2S < CuS B CuS < Ag2S < Bi2S3 C Ag2S < Bi2S3 < CuS D CuS < Bi2S3 < Ag2S 15 Use of the Data Booklet is relevant to this question. Impure copper obtained from copper ores can be purified by electrolysis as shown below. The cell potential is adjusted such that copper of the impure copper electrode dissolves and impurities such as silver, iron and zinc can be removed through this process. Which of the following statements is not correct regarding the above electrolytic process? A Electrode T contains impure copper. B Reduction occurs at electrode U. C Iron and silver impurities fall to the bottom as sludge. D Zinc impurity goes into the solution as Zn2+ ions. electrode U CuSO4(aq) electrode T

-7- 16 Use of the Data Booklet is relevant to this question. Which of the following would change colour when left to stand in the atmosphere? A an acidified solution of cobalt(II) nitrate