DHS Prelim P1 Qn

1 This question paper consists of 17 printed pages and 1 blank page. © DHS 2017 [Turn over Name: Index Number: Class: DUNMAN HIGH SCHOOL Preliminary Examination 2017 Year 6 H2 CHEMISTRY 9729/01 Paper 1 Multiple Choice 25 September 2017 1 hour Additional Materials: Data Booklet Optical Mark Sheet INSTRUCTIONS TO CANDIDATES 1 Write your name, index number and class on this question paper and the OTAS Mark Sheet. 2 There are thirty 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 separate Optical Mark Sheet. 3 Each correct answer will score one mark. A mark will not be deducted for wrong answer. 4 Any rough working should be done in this booklet. 5 The use of an approved scientific calculator is expected, where appropriate. 6 On the OTAS Mark Sheet, please shade the code as “Class/Index number”.

2 © DHS 2017 9729/01 [Turn over 1 Use of the Data Booklet is relevant to this question. Which sample of gas contains twice the number of atoms as 4 g of helium gas, He? A 22 g of carbon dioxide, CO2 B 8 g of methane, CH4 C 4 g of hydrogen, H2 D 12 g of steam, H2O 2 When 10 cm3 of a gaseous hydrocarbon was sparked with excess oxygen gas and cooled to room temperature, the gaseous mixture contracted by 30 cm 3. When the residual gas was passed through aqueous potassium hydroxide, there was a further contraction of 40 cm3. What is the hydrocarbon? A 2–methylpropene B propane C butadiene D butane 3 Ethanedioate ions, C 2O42–, are oxidised by acidif ied aqueous potassium manganate (VII) to give carbon dioxide. What volume of 0.020 mol dm –3 potassium manganate(VII) is required to completely oxidise 2.0 x 10–3 mol of the salt NaHC2O4.H2C2O4? The half equation for MnO4– is given below: MnO4– + 8H+ + 5e–  Mn2+ + 4H2O A 20 cm3 B 40 cm3 C 80 cm3 D 100 cm3

3 © DHS 2017 9729/01 [Turn over 4 The successive ionisation energies, in kJ mol–1, of elements G and H are given below. G 580 1820 2740 11600 14800 18400 23300 H 940 2050 2970 4140 6590 7880 14900 Which statements about elements G and H are true? 1 The first ionisation energy of G is lower than that of the element preceding it in the Periodic Table. 2 G and H forms a compound with the formula G3H2. 3 H has an outer electronic configuration ns2 np4. 4 When oxides of G and H are added separately to water containing Universal Indicator solution, the solution turns blue and red respectively. A 1 and 3 only B 3 and 4 only C 2, 3 and 4 only D 1, 2 and 4 only 5 Which graph does not describe the relationship between volume and pressure for a fixed mass of an ideal gas under constant temperature? A B C D V pV V 1/p V p pV V V V p

4 © DHS 2017 9729/01 [Turn over 6 The bond lengths and bond angles in the molecules of methane, ammonia and water may be represented as follow: C 0.109 nm N 0.101 nm O 0.096 nm methane ammonia water What causes this trend in the bond angles shown? 1 Increasing repulsion between hydrogen atoms as the bond length decreases. 2 Number of non–bonding electron pairs of the central atom in the molecule. 3 Non-bonding electron pair –bonding electron pair repulsion is great er than bonding electron pair–bonding electron pair repulsion. A 3 only B 1 and 2 only C 2 and 3 only D 1, 2 and 3 7 Equimolar samples of gaseous NH3 and HBr were injected into an evacuated flask maintained at a fixed temperature. Some white crystals of NH4Br were observed in the flask. Which is the only piece of information you would need to calculate the value of Kp? A initial amount of HBr used B mass of NH4Br formed at equilibrium C base dissociation constant, Kb, of NH3 D total pressure of the system at equilibrium 8 Use of the Data Booklet is relevant to this question. Nickel tetracarbonyl, Ni(CO)4, is an intermediate in the Mond process. It has a melting point of –17.2°C and a boiling point of 43°C. A 40.3 g sample of nickel tetracarbonyl is placed in a 10 dm 3 vessel under an atmosphere of neon gas at 20°C and a pressure of 1.0 atm. When the vessel is warmed to 60°C and the contents are allowed to reach equilibrium, 10% of the nickel tetracarbonyl has dissociated into nickel metal and carbon monoxide. What is the total pressure of the gases in the vessel at 60°C? [Mr of Ni(CO)4 = 170.7] A 2.04 atm B 1.97 atm C 1.37 atm D 0.837 atm 109.5° 107° 104.5°

5 © DHS 2017 9729/01 [Turn over 9 J is a monoacidic weak base with a pKb of 3.5. A total of 50 cm3 of 0.1 mol dm–3 of J was added dropwise to 20 cm3 of 0.1 mol dm–3 HNO3. Which pH curve correctly describes the changes in the pH of the resultant solution as J was added to HNO3? A B C D 3.5 10 Volume of J added / cm3 pH 20 <7 3.5 10 Volume of J added / cm3 pH 20 >7 10.5 20 Volume of J added / cm3 pH 30 <7 10.5 20 Volume of J added / cm3 pH 40 <7

6 © DHS 2017 9729/01 [Turn over 10 Consider the following solutions at 298K: solutions concentration / mol dm–3 NH3 (Kb = 1.8 × 10–5 mol dm–3) 0.010 CH3COOH (Ka = 1.8 × 10–5 mol dm–3) 0.010 NH4Cl 0.10 CH3COO–Na+ 0.10 Which sequence correctly ranks these solutions in increasing pH? A NH4Cl < CH3COO–Na+ < CH3COOH < NH3 B NH4Cl < CH3COOH < NH3 < CH3COO–Na+ C CH3COOH < NH4Cl < CH3COO–Na+ < NH3 D CH3COOH < NH4Cl = CH3COO–Na+ < NH3 11 The table below lists the Ksp values of some lead containing salts. salts Ksp value PbCrO4 2.8 × 10–13 PbCO3 7.4 × 10–14 Pb(OH)2 1.2 × 10–15 Pb3(AsO4)2 4.0 × 10–36 A student prepared four solutions containing x mol dm–3 of Pb2+ ions. She then added solutions containing an anion drop–wise to one of these Pb2+ containing solutions, as shown below. Which set –up will allow for the greatest volume of anion –containing solution to be added before a precipitate is formed? CrO42– (aq) y mol dm–3 CO32– (aq) y mol dm–3 OH– (aq) y mol dm–3 AsO43– (aq) y mol dm–3 A B C D

7 © DHS 2017 9729/01 [Turn over 12 Use of the Data Booklet is relevant to this question. Hexamine has an enthalpy change of combustion of –4288 kJ mol–1. 12.4 g of hexamine tablets were burnt to heat up 850 g of water. Given that the process was 75% efficient and temperature of the water increased from 10°C to 90 °C, what is the molar mass of hexamine? A 124.7 g mol–1 B 140.3 g mol–1 C 187.1 g mol–1 D 249.4 g mol–1 13 1 mol of unknown organic compound W was placed in a closed vessel. This closed system was kept at room temperature and pressure. The absolute entropy, S, of the system was measured over a period of time as shown in the graph below: At time t 1, 1 mol of unknown compound X was added into the closed vessel and the vessel was sealed again. What could be compounds W and X? W X A ethanol sodium metal B pent–2–ene liquid bromine C propanoic acid sodium carbonate D propanoic a