NJC Prelim P1 Question Paper

1 NJC SH2 Preliminary Examination 9729/01/17 NATIONAL JUNIOR COLLEGE SH2 PRELIMINARY EXAMINATION Higher 2 CANDIDATE NAME SUBJECT CLASS REGISTRATION NUMBER CHEMISTRY Paper 1 Multiple Choice Additional Materials: Multiple Choice Answer Sheet Data Booklet 9729/01 Thursday 14 Sept 2017 1 hour 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 30 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 16 printed pages.

2 NJC SH2 Preliminary Examination 9729/01/17 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: 1605648 65648 SH1 CT CM G or IP B SH2 Prelim cm2P

3 NJC SH2 Preliminary Examination 9729/01/17 [Turn Over For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 A mixture of two sulfur-containing gases, H 2S and CS 2, was burned in an excess of oxygen. H2S + 3 2O2  H2O + SO2 CS2 + 3O2  CO2 + 2SO2 Upon complete combustion followed by cooling back to room temperature, the gaseous mixture was first passed through acidified KMnO4. The volume contracted by 10.0 cm3. After which, the resulting gas was passed through aqueous sodium hydroxide, a further contraction of 2.0 cm3 occurred. All volumes are measured under the same conditions. What was the mole fraction of H2S in the mixture? A 0.333 B 0.500 C 0.750 D 0.833 2 Chromium has an oxidation state of +3 in its metal ore, chromite, FeCr 2O4. Pure chromium is extracted from chromite in several steps show below. FeCr2O4 Na2CrO4 Na2Cr2O7 Cr2O3 Cr Which shows the correct type of reaction involving chromium in steps I, II and III? Step I Step II Step III A displacement acid–base displacement B oxidation oxidation reduction C displacement oxidation oxidation D oxidation acid–base reduction Step I Step II Step III Al H+

4 NJC SH2 Preliminary Examination 9729/01/17 3 Use of the Data Booklet is relevant to this question. The amount of iron in a pill that contain iron( II) salts can be estimated by titration with KMnO4(aq). When a pill is dissolved in 10 cm 3 of dilute sulfuric acid and titrated against 0.40 mol dm −3 KMnO4, the E cell was measured against a standard hydrogen electrode and plotted as shown: Which statements are correct? 1 The number of moles of Fe2+ in the pill is 4.0 × 102 mol. 2 The value of Ecell at point X is 0.77 V. 3 The colour change at end point is from pink to pale green. A 1 and 2 only B 1 and 3 only C 2 and 3 only D 1 only vol of KMnO4 added / cm3 0 Ecell / V 20.0 x  10.0

5 NJC SH2 Preliminary Examination 9729/01/17 [Turn Over 4 The following graph represents the second ionisation energy trend of 9 consecutive elements in Periods 3 and 4. Which statement is correct? A Element C is in Group 3. B Element F has the lowest boiling point. C The ionic radius of ion of E is greater than that of ion of J. D The formula of the compound formed between elements D and G is D2G3. 5 Long-chain alkanes are converted on an industrial scale into alky lsulfates for use as detergents. One example is sodium lauryl sulfate shown below. Which statements can be deduced from the structure given? 1 The compound can dissolve in both polar and non-polar solvents. 2 The shape about the sulfur atom is square planar. 3 All the C–C–C bond angles are 109.5o. A 1, 2 and 3 B 1 and 2 only C 1 and 3 only D 2 and 3 only B C D E F G H I J second ionisation energy Element

6 NJC SH2 Preliminary Examination 9729/01/17 6 Which statement is true for a fixed amount of an ideal gas when temperature increases at constant pressure? (V = volume, p = pressure and T = temperature in K) A V remains constant. B pV T remains constant. C Density of the gas remains constant. D pV remains constant. 7 The reduction of iron ore, Fe2O3, by carbon monoxide is an exothermic reaction which occurs in the upper part of the furnace. Fe2O3(s) + 3CO(g)  2Fe(s) + 3CO2(g) H = −27 kJ mol−1 Given that Hf for CO2 (g) = −394 kJ mol−1 and Hf for CO (g) = −110 kJ mol−1, what is the standard enthalpy change of formation of Fe2O3(s)? A +257 kJ mol−1 B +825 kJ mol−1 C −257 kJ mol−1 D −825 kJ mol−1 8 Which value would be required to calculate the lattice energy for the hypothetical ionic compound BaF3 using Born-Haber cycle? A Third electron affinity of fluorine B Third ionisation energy of fluorine C Ba–F bond energy D F–F bond energy 9 A sample of X(g) with initial pressure of p atm is allowed to reach equilibrium at constant pressure. X(g) Y(g) + 2Z(g) The equilibrium partial pressure of X is 0.25p atm. What is the value of Kp? A 0.5p B 4.5p C 0.25p2 D 6.75p2

7 NJC SH2 Preliminary Examination 9729/01/17 [Turn Over 10 Which indicator is suitable for use in a titration of 0.1 mol dm –3 H2SO4 with 0.1 mol dm–3 of NH3? A Methyl orange (pH range 3.3 – 4.4) B Bromothymol blue (pH range 6.0 – 7.6) C Phenolphthalein (pH range 8.3 – 10.0) D None of the above 11 Magnesium hydroxide is extracted from the seawater as follows. Aqueous calcium hydroxide is added to seawater. Magnesium hydroxide is then filtered off. Ca(OH)2(aq) + MgCl2(aq)  Mg(OH)2(s) + CaCl2(aq) Which statement best explains why magnesium hydroxide is formed in the above reaction? A Magnesium is less electropositive than calcium. B The solubility product for Mg(OH)2 is lower than that for Ca(OH)2. C The enthalpy change of hydration for Mg2+ is less exothermic than for Ca2+. D The magnitude of the lattice energy of Mg(OH)2 is less than that of Ca(OH)2.

8 NJC SH2 Preliminary Examination 9729/01/17 12 P, Q and R react in aqueous solution according to the following equation: P + 3Q + 2R  T + U The kinetics of the above reaction was studied and the experimental results obtained are shown in the table below. Expt Volume of P /cm3 Volume of Q /cm3 Volume of R /cm3 Volume of water /cm3 Relative initial rate 1 10 10 10 20 16 2 10 5 20 15 32 3 5 5 10 30 4 4 10 5 10 25 8 What is the rate equation for the above reaction? A Rate = k[P][Q] B Rate = k[P][Q][R] C Rate = k[P][Q]2[R] D Rate = k[P][Q][R]2 13 Use of the Data Booklet is relevant to this question. A cell is set up by connecting a Cu2+/Cu half-cell and an acidified MnO4−/Mn2+ half-cell.