NYJC Prelim CHEM P1

NANYANG JUNIOR COLLEGE JC 2 PRELIMINARY EXAMINATION Higher 2 CHEMISTRY 9746/01 Paper 1 Multiple Choice 25 September 2009 1 hour Additional Materials: Mult iple 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 16 printed pages and 0 blank page. [Turn over

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 When 15 cm 3 of a gaseous hydrocarbon X were burned in 100 cm 3 of oxygen, the final gaseous mixture contained 60 cm 3 of carbon dioxide and 10 cm 3 of unreacted oxygen. [All gaseous volumes measured under identical conditions.] What is the formula of hydrocarbon X? A C3H6 B C4H10 C C4H8 D C3H8 2 Magnesium nitride is a yello w-green powder and it reacts with water according to the following equation : Mg 3N2 (s) + 6 H2O (l) → 2 NH3 (aq) + 3 Mg(OH)2 (s) If 20 g of water are mixed with an excess of powder and any solids are filtered away, what is the appr oximate volume (in cm 3) of 0.82 mol dm -3 of HCl that is required to neutralize the ammonia produced ? A 150 B 300 C 450 D 900 3 Which one of the species has less electrons than neutrons and less neutrons than protons ? Particles A- B2+ C3+ D3- Neutrons 18 17 16 16 Nucleons 37 34 33 31 A A - B B2+ C C3+ D D3- 4 Which one of the following corresponds to the configuration of the three electrons of the highest energy for one of the elements in Group III? A 1s 2 2s1 B 2s1 2p2 C 3p3 D 4s2 4p1 H2 Chemistry 9746/01/NYJC J2/09PX [Turn Over

3 5 Which of the following pairs have different types of bonding and structure? A BeCl2 AlCl3 B SiO2 SiC C NaF AlF3 D ScCl3 AlCl 3 6 Which of the following pairs does Species X have a larger bond angle than Species Y Species X Species Y A SO 2 PI 3 B SF6 XeF 4 C CH4 SiCl 4 D H2S NH 3 7 Pure nitrosyl chloride, NOCl gas was heated at 300 oC in a 1.0 dm3 container. At equilibrium, the total pressure wa s 1.23 atm and the NOCl gas pressure was 0.810 atm. 2NOCl(g) 2NO(g) + CI2(g) What is the equilibrium constant, Kp at 300oC? A 0.00418 atm B 0.0167 atm C 0.0597 atm D 0.0915 atm H2 Chemistry 9746/01/NYJC J2/09PX [Turn Over

4 8 The value of pV is plotted against p for 2 gases, A and B, where p is the pressure and V is the volume of the gas. Which of the following could be the identities of the gases? Gas X Gas Y A 0.5 mol of H2 at 25 ºC 0.5 mol of H2 at 50 ºC B 0.5 mol of H2 at 25 ºC 1 mol of SO2 at 25 ºC C 0.25 mol of SO2 at 25 ºC 0.5 mol of H2 at 25 ºC D 1 mol of SO2 at 25 ºC 0.5 mol of H2 at 25 ºC 2x x pV p 0 Gas Y Gas X 9 For the hypothetical ionic compound CaH, which value is needed to estimate its lattice energy? A electron affinity of hydrogen B first electron affinity of calcium C Ca-H bond energy D standard enthalpy change of formation of CaH2 10 Consider the equation: 2SO 2 (g) + O2 (g) → 2SO3(g) ΔH = -199 kJ mol-1, ΔS = -190 J K-1 mol-1 A In formation of products, the system becomes more disordered B The products are energetically less stable than the reactants C As temperature increases, the reaction becomes more spontaneous D The reaction is spontaneous under standard conditions H2 Chemistry 9746/01/NYJC J2/09PX [Turn Over

5 11 The kinetics of the reaction between iodide and peroxodis ulphate can be investigated by varying the volume of the reactants used. T he two reactants are mixed in the presence of a known amount of Na2S2O3 and a little starch. The time taken for an intense blue colour to be observed is then determined. Experiment Vol used / cm3 Time 1.0 mol dm-3 KI 0.040 mol dm-3 Na2S2O8 H2O (l) t / s 1 10.0 5.0 25.0 170 2 15.0 5.0 20.0 113 3 15.0 10.0 15.0 56.5 4 20.0 20.0 0.0 x What is the value of x in Experiment 4? A 11 B 21 C 85 D 1360 12 Given that a reaction has the overall equation and proceeds via the following mechanism shown below : 2 P + Q → R + S Step 1 : P + Q → R + T (fast) H = +45 kJ mol -1 Step 2 : P + T → S (slow) H = -98 kJ mol-1 Which of the following statement is true? A The overall order of reaction is 2 B The enthalpy change for the reaction is -53 kJ mol-1 C The activation energy needed for Step 1 is + 45 kJ mol-1 D Compound T is acting as a catalyst H2 Chemistry 9746/01/NYJC J2/09PX [Turn Over

6 14 The following reaction has a negative E θ cell so that it does not occur under standard conditions. 2NO 3 ─ (aq) + 8H+ (aq) + 6Cl─ (aq) 2NO (g) + 4H2O (l) + 3Cl2 (g) Nevertheless, the reaction may be made to proceed under non-standard conditions. Which of the following would NOT help the reaction to proceed? A Increase in acidity B Addition of potassium nitrate C Addition of potassium iodide D Addition of bromine 13 The electrochemical cells are set up as shown below. The e.m.f in volts is shown on each voltmeter. 0.45 1.10 0.52 These e.m.f’s indicate that the order of reactivity of the metals, from weakest reducing agent to strongest reducing agent is A X, Cu, Y, Z B Cu, Z, X, Y C Z, Cu, X, Y D Y, X, Z, Cu Z V V V +ve - ve +ve -ve +ve -ve 0.1 mol dm3 Z2+ (aq) Cu Z Cu Cu Y X 0.1 mol dm3 Cu2+ (aq) 0.1 mol dm3 X2+ (aq) 0.1 mol dm3 Y2+ (aq) 0.1 mol dm3 0.1 mol dm3 2+ Cu2+ Cu (aq) (aq) H2 Chemistry 9746/01/NYJC J2/09PX [Turn Over

7 15 Given the numerical value for the K sp of calcium phosphate, Ca 3(PO4)2 is 2.07 x 10⎯33, its solubility in water at 25 oC is A 1.03 x 10⎯6 mol dm⎯3 B 3.42 x 10⎯7 mol dm⎯3 C 2.28 x 10⎯7 mol dm⎯3 D 1.14 x 10⎯7 mol dm⎯3 16 For the oxides of Period 3 elements (Na to P), which property decreases from Na 2O to SiO2 and also from SiO2 to P4O10 ? A Covalent character B Melting point C pH when mixed with water D Solubility in aqueous alkali 17 Concentrated sulphuric acid is added to separate samples of sodium chloride, sodium bromide and sodium iodide. What are the halogen-containing substances produced? A Cl2, Br2 and I2 only B HCl, Br2 and I2 only C HCl, HBr and HI only D HCl, HBr, HI, Br2 and I2 only 18 Group VII elements and their hydrogen compounds exhibit trends in properties. Which of these properties increases down the group from Cl  Br  I ? A the hydrogen-halogen bond dissociation energy B the oxidizing power of the elements C the strength of the van der Waals’ forces between halogen molecules D the thermal stability of hydrogen halides H2 Chemistry 974