JJC H1 Chemistry 8872 H1 Prelim Paper 1 and Solutions

JURONG JUNIOR COLLEGE PRELIMINARY EXAMINATION 2008 H1 CHEMISTRY PAPER 1 8872 / 1 Friday 22 August 2008 50 minutes INSTRUCTIONS TO CANDIDATES: Do not open this question booklet until you are told to do so. Write your name and class on the answer sheet in the spaces provided. 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. INFORMATION FOR CANDIDATES: Each correction answer will score one mark. A mark will not be deducted for a wrong answer. Any rough working should be done in this booklet. A Data Booklet is provided. _____________________________________________________________________ This question booklet consists of 10 printed pages, including this page. [Turn over]

SECTION A (25 MARKS) For each question there are four possible answers, A, B, C and D. Choose the one you consider to be correct. 1. How many atoms of carbon are present in 18 g of glucose C6H12O6? A 6.0 x 1022 B 3.6 x 1023 C 6.0 x 1023 D 3.6 x 1024 2. What is the minimum volume of air required for complete combustion of 10 cm 3 of a hydrocarbon, C3H4? Assume that air contains one-fifth oxygen by vo lume and that both gases are measured at the same temperature and pressure. A 40 cm3 B 50 cm3 C 200 cm3 D 250 cm3 3. Nitrogen dioxide reacts with iodide ions under acidic conditions according to the equation shown. NO2 + 2I− + 2H+ Æ NO + I2 + H2O How many moles of electrons are gained by one mole of nitrogen dioxide? A 1 B 2 C 3 D 4 4. The electronic configurations of four elements are given. Which of these elements has the lowest first ionisation energy? A 1s2 2s2 2p3 B 1s2 2s2 2p4 C 1s2 2s2 2p6 3s2 D 1s2 2s2 2p6 3s2 3p1 Page 2 of 10

5. Use of the Data Booklet is relevant to this question. The successive ionisation energies, in kJ mol−1, of an element X are given below. 947 1798 2735 4837 6043 12310 13298 What could X be? A 33As B 40Zr C 49In D 52Te 6. Which of the following particl es would, on losing an electron, have a half-filled set of p orbitals? A C− B N C N− D O+ 7. Silicon carbide (carborundum) has a similar structure to diamond. Silicon carbide can be used as A a lubricant B a tip for cutting tools C an electrical conductor D a substitute for pencil ‘lead’ 8. Which of the following molecules do not have all the atoms lying on the same plane? A H 2O B PH3 C AlCl3 D ICl3 9. Which of the following molecules will not form a hydrogen bond with another of its own molecules? A CH 3CHO B CH3NH2 C CH3OH D NH3 Page 3 of 10

10. Zinc is extracted from zinc sulphide by a process which begins with roasting of the sulphide ore in air. 2ZnS(s) + 3O2(g) → 2ZnO(s) + 2SO2(g) Given that ∆Hf θ for ZnS(s) = −200 kJ mol-1, ∆Hf θ for ZnO(s) = −348 kJ mol-1, and ∆Hf θ for SO2(g) = −297 kJ mol-1, what is the ∆Hθ for this reaction? A −445 kJ mol-1 B −890 kJ mol-1 C +890 kJ mol-1 D −1690 kJ mol-1 11. The enthalpy change for the neutralisation given below is –57 kJ mol-1. HCl (aq) + NaOH (aq) NaCl (aq) + H2O (l) By using this information, predict a value for the enthalpy change given below. CH 3COOH (aq) + NaOH (aq) CH3COONa (aq) + H2O (l) A – 55 kJ mol-1 C – 114 kJ mol-1 B – 57 kJ mol-1 D – 120 kJ mol-1 12. Which graph would confirm that the rate of decomposition of hydrogen peroxide is first order with respect to the concentration of hydrogen peroxide? A C B D 0 rate of decomposition of H 2O2 [H2O2] [H2O2] rate of decomposition of H 2O2 0 0 rate of decomposition of H 2O2 [H2O2] rate of decomposition of H 2O2 0 [H2O2] Page 4 of 10

13. Which statement about the effect of a catalyst on a reversible reaction is correct? A It increases the equilibrium constant for the forward reaction. B It increases the yield of product in an equilibrium. C It increases the rate constant for both the forward reaction and the reverse reaction. D It increases the rate constant for the forward reaction but not that for the backward reaction. 14. An enzyme, found in stomach, operates at maximum efficiency when in an aqueous solution buffered at pH 5. Which combination of subst ances when dissolved in 10 dm 3 of water, would give the necessary buffer solution? A 1 mol HCl and 1 mol of CH 3COOH B 1 mol CH3COOH and 1 mol of CH3COONa C 1 mol HCl and 1 mol of CH3COONa D 1 mol of CH3COONH4 15. The following graphs show how three properti es of the elements, Na to P, and their compounds, vary with proton number. Graph 1 Graph 2 Graph 3 What properties are shown by the three graphs? Graph 1 Graph 2 Graph 3 A Melting point of oxide Melting point of chloride Conductivity of element B Melting point of chloride Melting point of element Melting point of oxide C Melting point of oxide Conductivity of element Melting point of chloride D Melting point of element Melting point of chloride Conductivity of element 11 12 13 14 15 proton number 11 12 13 14 15 proton number 11 12 13 14 15 proton number Page 5 of 10

16. An element V forms an oxide of high melting point which is sparingly soluble in water. The chloride of V is a solid at room temperature, has high melting point and dissolves in water to from a weakly acidic solution of pH 6.5. What is element V? A Sodium B Magnesium C Silicon D Phosphorus 17. What is the product when propene is oxidised with cold dilute potassium manganate(VII) A CH3CH(OH)CH2OH B CH3CH2CH2OH C CH3CH2CHO D CH3COCH3 18. Which compound cannot be obtained from propene in a single reaction? CH A C B D H 3 19. Which property of benzene may be directly attributed to the stability associated with its delocalised electrons? A It has a low boiling point B It does not conduct electricity C Its enthalpy change of formation is positive D It tends to undergo substitution rather than addition reactions C = C propene HH − C − C − H CH3 H C− H CH3 H N HH C − C − H H H − C − C − H CH3 H OH H OH − C − C − H CH H Br HH Page 6 of 10

20. A chlorine compound with the following stru ctural formula is boiled with aqueous sodium hydroxide. How many chlorine atoms in each molecule will be substituted upon hydrolysis? A 0 B 1 C 2 D 3 Cl ClH2C 21. The compound C3H7Br undergoes a sequence of reactions as follows. n C3H7Br X Y Z + silver mirror What could be the formulae for X, Y and Z? X Y Z A CH3CH2CH2OH CH 3CH2COOH CH 3CH2CHO B CH3CH2CH2OH CH 3CH2CHO CH 3COOH C CH3CH2CH2OH CH 3CH2CHO CH 3CH2COOH D CH3CH(OH)CH3 CH 3COCH3 CH 3COOH 22. The volatile liquid, Fluothane, CF3CHBrCl, is a widely used anaesthetic. Which statement about Fluothane is incorrect? A It is chemically inert. B It may cause depletion of the ozone layer. C It can form hydrogen bonds between its molecules. D It may undergo nucleophilic substitution with ammonia. aq OH− acidified K2Cr2O7 Tollen's reagent 23. Which of the following compounds reacts with its own oxidation product (an oxidation which involves no loss of carbon) to give a sweet smelling liquid? A propanal B propanoic acid C propanone D propan-1-ol Page 7 of 10

24. Which st