NJC 2018 SH1 H1 Promo Paper 1

1 NJC SH1 Promotional Examination 8873/01/18 [Turn Over NATIONAL JUNIOR COLLEGE SH1 PROMOTIONAL EXAMINATION Higher 1 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 8873/01 Monday 1 October 2018 40 minutes READ THESE INSTRUCTIONS FIRST Write in soft pencil. Do not use staples, paper clips, highlighters, glue or correction fluid. Write your name, subject class and registration number on the Answer Sheet in the spaces provided unless this has been done for you. There are 20 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 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. The use of an approved scientific calculator is expected, where appropriate. This paper consists of 9 printed pages.

2 NJC SH1 Promotional Examination 8873/01/18 Instructions on how to fill in the Optical Mark Sheet Example: Shade the index number in a 5 digit format on the optical mark sheet: 2nd digit and the last 4 digits of the Registration Number. Student Examples of Registration No. Shade: 1805648 85648 SH1 CT CM G or IP B SH1 Promo cm1X

3 NJC SH1 Promotional Examination 8873/01/18 [Turn Over For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1 The table shows the absolute abundance of a sample of naturally occurring isotopes of zinc. Absolute Abundance Zn30 64 100 Zn30 65 80 Zn30 67 20 Zn30 68 10 What is the relative atomic mass of this sample of zinc? A 64 B 64.9 C 68.1 D 72.2 2 Use of Data Booklet is relevant to this question. In research on the atomic nucleus, scientists have been comparing the stability of isotopes with the same neutron : proton ratio. Which isotope has the same neutron : proton ratio as 10B? A 32S B 32P C 40K D 40Ar 3 15 cm3 of a hydrocarbon was completely combusted in 75 cm 3 of oxygen. The final gaseous mixture contained 30 cm 3 of carbon dioxide and 30 cm 3 of unreacted oxygen. All gaseous volumes were measured under room temperature and pressure. What is the molecular formula of the hydrocarbon? A CH4 B C2H4 C C2H6 D C3H6 4 0.0050 mol of a metal oxide, Z2Ox, reacted exactly with 0.0060 mol of acidified potassium manganate(VII) solution. Given that the oxidation state of Z in the product is +6, what is the value of x? A 1 B 2 C 3 D 4

4 NJC SH1 Promotional Examination 8873/01/18 6 Which equation represents the second ionisation energy of Fe? A Fe(s) ⎯→ Fe2+ (s) + 2e− B Fe(s) ⎯→ Fe2+ (g) + 2e− C Fe+ (s) ⎯→ Fe2+ (s) + e− D Fe+ (g) ⎯→ Fe2+ (g) + e− 7 Cyanamide, NH2CN, can react with boron trifluoride, BF3. Which structure represents the product? A B C D 5 A proton and an electron both move at the same speed perpendicular to a uniform electric field. What deflection is observed? A They are deflected in opposite directions. The electron is deflected more. B They are deflected in opposite directions. The proton is deflected more. C They are deflected in the same direction. The electron is deflected more. D They are deflected in the same direction. The proton is deflected more.

5 NJC SH1 Promotional Examination 8873/01/18 [Turn Over 8 The characteristic smell of garlic is due to alliin . When garlic is cut, an enzyme releases alliin because alliin has the right shape to fit the enzyme molecule. What would you expect the bond angles x, y and z to be in a molecule of alliin? x y z A 120° 107° 109.5° B 120° 120° 109.5° C 180° 90° 90° D 180° 120° 90° 9 Which statements about AlCl3 are correct? 1 The aluminium atom has an incomplete octet. 2 The AlCl3 molecule is trigonal planar in shape. 3 There are permanent dipole – permanent dipole interactions between AlCl3 molecules. A 1, 2 and 3 B 1 and 2 only C 1 only D 2 and 3 only 10 Silicon dioxide, SiO2 is a refractory material which melts at a very high temperature. Which one of the following structures exists in SiO 2 that helps to explain the above property? A A giant ionic lattice structure with electrostatic forces of attraction between silicon and oxygen ions. B A simple molecular structure with covalent bonds between silicon and oxygen atoms and weak temporary dipole-induced dipole interactions between SiO2 molecules. C A layered structure with covalent bonds between silicon and oxygen atoms and weak temporary dipole-induced dipole interactions between the layers. D A giant molecular structure with strong covalent bonds between silicon and oxygen atoms forming a 3 dimensional network.

6 NJC SH1 Promotional Examination 8873/01/18 11 For which of the following reactions does the enthalpy value represent both a standard enthalpy change of combustion and a standard enthalpy change of formation? A CO(g) + ½O2(g) → CO2(g) B 2C(s) + O2(g) → 2CO(g) C C(s) + O2(g) → CO2(g) D C(s) + 2O(g) → CO2(g) 13 Which reactions have a positive enthalpy change of reaction? 1 formation of Al2O3 solid from gaseous Al3+ and O2–. 2 Br2(g) 2Br(g) 3 Na(g) Na+(g) + e– A 1, 2 and 3 are correct. B 1 and 2 are correct. C 2 and 3 are correct. D Only 3 is correct. 12 The enthalpy changes for three reactions are given below: Na(s) → Na+(g) + e H = +601 kJ mol−1 H+(aq) + OH−(aq) → H2O(l) H = −58 kJ mol−1 2Na+(g) + 2H+(aq) + 2e− → 2Na+(aq) + H2(g) H = −1700 kJ mol−1 What is the enthalpy change for H1? Na(s) + H2O(l) Na+(aq) + OH−(aq) + ½H2(g) A −191 kJ mol−1 C −685 kJ mol−1 B −307 kJ mol−1 D −1041 kJ mol−1 Na+(g) + e + H+(aq) + OH−(aq) H1

7 NJC SH1 Promotional Examination 8873/01/18 [Turn Over 14 In monitoring the reaction between sodium thiosulfate and hydrochloric acid by the initial rate method, the following graph was obtained. The initial concentration of sodium thiosulfate was the same in all experiments. Rate What deductions can be made from the graph? 1 The order of reaction with respect to hydrochloric acid at low concentrations is 1. 2 The order of reaction with respect to hydrochloric acid at high concentrations is 0. 3 When [sodium thiosulfate] is high, the rate is independent of [sodium thiosulfate]. A 1 only. B 2 and 3 only. C 1 and 2 only. D 1, 2 and 3. 15 An experiment was carried out to investigate the rate of reaction between ammonium peroxodisulfate, (NH4)2S2O8, an oxidising agent, and potassium iodide, KI. The initial concentrations of the (NH4)2S2O8 and KI solutions in the mixture together with the time taken for the mixture to darken for the various experimental runs are given below. Expt No. [(NH4)2S2O8] / mol dm–3 [KI] / mol dm–3 time / s 1 0.10 0.20 35 2 0.05 0.20 70 3 0.10 0.067 105 4 0.02 0.75 y What is the value of y in experiment 4? A 40 s B 47 s C 60 s D 72 s [HCl]

8 NJC SH1 Promotional Examination 8873/01/18 16 The diagram shows the reaction pathway diagram for an uncatalysed reaction. The reaction is then catalysed.