HCI Prelim P1

This document consists of 16 printed pages. HWA CHONG INSTITUTION C2 Preliminary Examinations Higher 2 CANDIDATE NAME CT GROUP 14S CENTRE NUMBER INDEX NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Optical Mark Sheet (OMS) Data Booklet 9647/01 18 September 2015 1 hour READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, glue or correction fluid. Complete the information on the optical mark sheet (OMS) as shown below. 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 your choice in soft pencil on the OMS. 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. The use of an approved scientific calculator is expected, where appropriate.

2 © Hwa Chong Institution 2015 9647 / 01 / C2 Prelim 2015 SECTION A For each question, there are four possible answers A, B, C and D. Choose the one you consider to be correct. 1 10 cm3 of a hydrocarbon wa s mixed with 50 cm3 of oxygen and combusted completely. After the resulting gas mixture was cool ed and passed through aqueous sodium hydroxide, the volume of the residual gas mixture was found to be ¼ the volume of the original gas mixture before combustion. All volumes were measured at room temperature and pressure. What is the formula of the hydrocarbon? A C2H4 B C2H6 C C3H6 D C3H8 2 Equal volumes of 1 mol dm −3 hydrogen sulfide and sulfur dioxide (each containing a different isotope of sulfur) are mixed to precipitate sulfur according to the equations shown below: H2 32S(aq) → 32S(s) + 2H+(aq) + 2e− 34SO2(aq) + 4H+(aq) + 4e− → 34S(s) + 2H2O(l) What is the relative atomic mass of the sulfur precipitated? A 32.1 B 32.7 C 33.0 D 33.3 3 Use of the Data Booklet is relevant to this question. Which particle would, on losing an electron, have a half-filled set of d orbitals? A Cr B Mn2+ C Fe3+ D Cr2+

3 © Hwa Chong Institution 2015 9647 / 01 / C2 Prelim 2015 4 Which of the following pairs of liquids are immiscible? A (CH3)2CO and H2O C CCl4 and H2O B CH2Cl2 and (CH3)2CO D CCl4 and CH3CHO 5 A solid E has the following physical properties.  It is insoluble in non-polar solvents.  It melts at 1290 oC.  It conducts electricity in both aqueous and molten states. What is the likely structure of E? A a giant ionic structure C a giant covalent structure B a simple covalent structure D a metallic structure 6 The value of pV/RT is plotted against p for one mole of each of the two non -ideal gases L and M, where p is the pressure, V is the volume and T is the temperature of the gas. Which of the following pairs of gases could be L and M? L M A HCl F2 B CH4 C2H6 C CH3CH2CH3 CH3Cl D N2 O2

4 © Hwa Chong Institution 2015 9647 / 01 / C2 Prelim 2015 7 Which of the following is involved in determining the enthalpy change of a chemical reaction? A The number of steps involved in the chemical reaction B The mechanism of the reaction C The initial and final states of the reacting system D The activation energy of the reaction 8 For which process is the enthalpy change always negative? A Dissolving a compound in water B Forming an ion from an atom C Synthesizing a compound from its elements D Burning an element in oxygen 9 The rate for the reaction 2XO(g) + O2(g)  2XO2(g) was investigated by varying the partial pressures of XO and O2. The results are shown in the table below. partial pressure of XO/ atm 1.00 1.00 0.25 p partial pressure of O2/ atm 1.00 0.50 1.00 0.50 relative rate 1.00 0.50 0.25 0.125 What is the value of p in the table? A 0.125 B 0.25 C 0.50 D 1.00 10 The age of a rock sample may be determined by rubidium -strontium dating, in which rubidium-87 decays to strontium-87. This radioactive decay is a first-order reaction with a half-life of 4.88 × 1010 years. Assuming the rock sample contained no strontium-87 initially, what is the age of the rock sample if the molar ratio of rubidium-87 to strontium-87 in the sample is now 1:7? A 6.97 × 109 years B 1.63 × 1010 years C 1.46 × 1011 years D 3.42 × 1011 years

5 © Hwa Chong Institution 2015 9647 / 01 / C2 Prelim 2015 11 Which of the following statements involving the Haber process is correct? N2(g) + 3H2(g) ⇌ 2NH3(g); H < 0 A At equilibrium, the rate constants of the forward reaction and backward reaction are the same. B The equilibrium yield of NH3 can be improved by using powdered iron. C The activation energy of the forward reaction is greater than that of the backward reaction. D The equilibrium constant decreases with increasing temperature. 12 The numerical values of the solubility products at 25 C for AgC l and Ag I are 1.6 x 10–10 and 8.0 x 10–17 respectively. What is the equilibrium constant for the reaction below? AgCl(s) + I–(aq) AgI(s) + Cl–(aq) A 1.3 x 10–26 C 1400 B 5.0 x 10–7 D 2.0 x 106 13 Which of the following solutions will form an alkaline buffer? A 50 cm3 of 0.10 mol dm–3 NaOH added to 25 cm3 0.10 mol dm–3 CH3CO2 –Na+. B 25 cm3 of 0.10 mol dm–3 NaOH added to 50 cm3 0.10 mol dm–3 CH3CO2H. C 25 cm3 of 0.10 mol dm–3 NaOH added to 50 cm3 0.10 mol dm–3 CH3NH3 +Cl–. D 50 cm3 of 0.10 mol dm–3 NaOH added to 50 cm3 0.10 mol dm–3 CH3NH3 +Cl–. 14 Two sodium chloride solutions of different concentrations were electrolyzed at 1 atm and 298 K. Which of the following correctly describes the colour of the litmus paper when placed at the respective electrodes of each solution? [NaCl(aq)] = 0.001 mol dm3 [NaCl(aq)] = 5.0 mol dm3 cathode anode cathode anode A blue red blue white B blue white blue red C red blue white blue D red blue red blue

6 © Hwa Chong Institution 2015 9647 / 01 / C2 Prelim 2015 15 The oxide and chloride of an element F are separately mixed with water. The two resulting solutions have the same effect on litmus. What is element F? A aluminium B magnesium C phosphorus D silicon 16 A solid metal chloride with the formula, MCl2, was analysed to yield the following results.  The solid is soluble in water.  Precipitation did not occur when NaOH(aq) is added.  White precipitate observed when H2SO4(aq) is added. What is the identity of the cation? A Mg2+ B Pb2+ C Zn2+ D Ba2+ 17 When a white solid G reacts with concentrated H 2SO4, the products include pungent-smelling gases and a dark brown solution containing a yellow solid. When aqueous sodium thiosulfate is added, the solid remains but the dark brown colour disappears. What is G? A AgNO3 B CaCO3 C NaBr D KI 18 Which statement correctly defines a transition element? A Transition elements exhibit more than one oxidation state in their compounds. B Transition elements form many coloured compounds. C Transition elements have partially filled d orbitals. D Transition elements or their compounds are widely used as catalysts.

7 © Hwa Chong Institution 2015 9647 / 01 / C2 Prelim 2015 19 A reaction scheme is shown below. How can the three steps be classified? step 1 step 2 step 3 A addition hydrolysis condensation B addition oxidation substitution C substitution oxidation substitution D reduction hydrolysis condensation 20 Which of the following compounds could be formed when dichloromethane is reacted with excess chlorine in the presence of sunlight? A CHCl3 and H2 B CHCl3 and CH2ClCCl3 C